LIBRARY 

UNIVERSITY  OF 
CALIFORNIA 
SANTA  CRUZ 


QH 
43! 


INHERITANCE  OF  ACQUIRED  CHARACTERS 


Eugenio    Rignano 


UPON  THE 


Inheritance  of  Acquired 
Characters 


A  HYPOTHESIS  OF  HEREDITY,  DEVELOPMENT, 
AND  ASSIMILATION 


AUTHORIZED  ENGLISH  TRANSLATION 
BY 

BASIL  C.  H.  HARVEY 

ASSISTANT  PROFESSOR  OF  ANATOMY,  UNIVERSITY  OF  CHICAGO 


WITH  AN  APPENDIX 

UPON  THE  MNEMONIC  ORIGIN   AND    NATURE 
OF  THE  AFFECTIVE  OR  NATURAL  TENDENCIES 


CHICAGO 

THE  OPEN  COURT  PUBLISHING  CO. 
191 1 


Copyright,  1911, 

The  Open  Court  Puh.  Company, 
Chicago. 


CONTENTS 

INTRODUCTION    5 

CHAPTER  I. 

Ontogeny,  as  a  Recapitulation  of  Phylogeny  suggests  the  Idea 
of  a  continuous  Action  exerted  by  the  Germ  Substance 
upon  the  Soma  throughout  the  whole  of  Development....  II 

CHAPTER  II. 

1.  Phenomena   which  indicate   a  continuous  formative   Action 

which  is  exerted  by  Parts  of  the   Soma  upon  the  other 
Parts  throughout  the  Whole  of  Development  19 

2.  Hypothesis  of  the  Nature  of  the  formative  Stimulus 29 

CHAPTER  III. 

1.  Phenomena  which  point  to  the  Existence  of  a  central  Zone 

of  Development    . . 53 

2.  Hypothesis  of  the  Structure  of  the  germinal  Substance 76 

CHAPTER  IV. 

1.  Phenomena  which  refute  simple  Epigenesis   104 

2.  Phenomena  which  refute  Preformation  121 

3.  Inadmissibility  of  a  homogeneous  germ  Substance 144 

4.  Inadmissibility  of  preformistic  Germs 150 

CHAPTER  V. 
The  Question  of  the  Inheritance  of  acquired  Characters 159 

CHAPTER  VI. 

The  most  important  of  the  existing  biogenetic  Theories  in  Rela- 
tion to  the  Inheritance  of  acquired  Characters  224 

CHAPTER  VII. 

The  centroepigenetic  Hypothesis  and  the  Explanation  of  In- 
heritance afforded  by  it  289 

CHAPTER  VIII. 

The  Phenomenon  of  Memory  and  the  vital  Phenomenon 316 

Conclusion    356 

Appendix    359 

Index    ,401 


"Some  deny  flatly  the  possibility  df  ever  arriving  at 
an  understanding  of  the  nature  of  life.  But  if  we  ask 
ourselves  in  what  this  understanding  of  the  nature  of  life 
could  consist,  from  the  point  of  view  of  positive  philos- 
ophy, zve  have  no  difficulty  in  recognizing  that  such  an 
understanding  must  be  reduced  to  comparing  vital  phe- 
nomena with  some  physico-chemical  model  already  known, 
suitably  modified  by  the  particular  special  conditions  im- 
posed upon  it  so  that  just  these  special  conditions  shall 
determine  the  differences  which  exist  between  this  vital 
phenomenon  and\  that  phenomenon  of  the  inorganic  world 
most  closely  related  to  it.  If  this  be  so,  it  is  then  the  duty 
of  science  emphatically  to  refuse  to  give  up  the  attempt  to 
understand  the  nature  of  living  matter,  for  that  would  be 
to  belie  the  Spirit  of  all  scientific  endeavor.  For  whether 
it  be  clearly  recognized  or  not,  it  is  just  this  search  for  the 
nature  of  the  vital  principle  which  properly  constitutes  the 
principal  object  and  the  final  goal  of  all  biologic  study  in 
general." — E.  RIGNANO,  in  "Acquired  Characters/'  p. 
334- 


TRANSLATOR'S    PREFACE 

Rignano  is  a  student  of  Biology  who  has  also  the 
training  of  an  engineer  and  physicist.  His  attack  on  bio- 
logical problems  is  from  that  side.  In  this  book  he  offers 
an  explanation  on  a  physical  basis  of  assimilation,  cell  di- 
vision, and  the  biogenetic  law  of  recapitulation  in  ontog- 
eny, and  he  suggests  a  mechanism  whereby  the  inheritance 
of  acquired  characters  may  be  effected. 

Such  a  study  of  the  most  fundamental  and  difficult  of 
biological  problems  can  not  fail  to  be  of  the  greatest  in- 
terest to  all  students  of  science.  It  points  out  a  way  to 
the  understanding  of  the  essential  nature  of  living  matter. 
Therefore  the  translator  has  gladly  consented  to  prepare 
for  publication  this  translation  first  made  for  his  own  sat- 
isfaction. It  has  been  revised  by  the  author. 

University  of  Chicago,  1911. 

BASIL  HARVEY, 


PREFACE  TO  THE  ENGLISH  EDITION 

This  work  which  appeared  first  in  French  in  1906  and 
later  in  German  and  Italian  now  appears  after  some  years 
in  English  thanks  to  the  interest  shown  by  several  Eng- 
lish and  American  biologists  and  philosophers,  who  have 
expressed  a  desire  to  have  its  circulation  facilitated 
among  the  savants  of  their  countries.  This  new  indica- 
tion of  the  growing  favor  acquired  in  a  short  time  by  the 
theories  here  advanced,  notwithstanding  the  author's  fear 
that  their  novelty  would  stand  somewhat  in  the  way  of 
their  reception,  is  the  best  reward  he  could  desire  for  the 
great  difficulty  he  has  encountered  in  the  study  of  these — 
the  most  fundamental  problems  of  biology.  And  he 
wishes  to  pay  here  his  sad  and  affectionate  respect  to  the 
revered  memory  of  Professor  C.  O.  Whitman,  one  of  the 
first  to  interest  himself  in  this  English  edition,  and  at 
the  same  time  to  express  his  gratitude  to  his  friend  Dr. 
Basil  Harvey  for  the  great  care  which  he  has  given  to  the 
translation,  as  well  as  to  Dr.  Paul  Carus  and  The  Open 
Court  Publishing  Co.,  who  have  been  so  good  as  to  be- 
come the  publishers. 

Milan,  March,  1911.  E.  R. 


INTRODUCTION 

The  question  of  the  inheritance  of  acquired  characters 
is  one  which,  by  its  generality,  by  its  importance  for  the 
theory  of  the  origin  of  species,  and  by  its  close  connec- 
tion with  still  more  difficult  questions  concerning  the 
essential  nature  of  life  lying  in  the  border  land  between 
physical  chemistry  and  biology,  passes  beyond  the  con- 
fines of  pure  biology,  and  enters  the  wider  field  of  posi- 
tive philosophy  in  the  sense  of  August  Comte,  that  is  of 
scientific  philosophy,  which  concerns  itself  with  the  most 
general  results  of  the  various  sciences  and  with  their 
fundamental  interrelations.  Is  it  any  wonder  then  that 
this  much  discussed  but  unsolved  question  excites  the 
keenest  interest  in  philosophers  and  even  induces  some  of 
them  though  they  are  not  specialists,  to  attempt  to  study 
it  thoroughly  utilizing  the  abundant  and  valuable  mate- 
rial which  biologists  and  naturalists  can  now  supply  ? 

It  is  so  with  the  author  of  the  present  study. 

Formerly  when  he  had  not  yet  formed  any  fixed  and 
definite  opinion  upon  this  subject,  he  had  been  inclined  in 
a  few  philosophical  and  sociological  studies  to  prefer 
Weismann's  theory  of  the  non-inheritance  of  acquired 
characters  to  the  contrary  theory  of  Lamarck.  The  rea- 
son for  this  inclination  even  though  no  logically  tenable 
opinion  had  been  formed,  lay  in  the  demonstrated  inabil- 
ity of  any  of  the  biological  theories  which  had  then  been 

5 


6  Introduction 

devised  to  give  any  explanation  whatever,  even  an  un- 
satisfactory one,  of  the  mechanism  of  that  inheritance. 
Yet  the  author  never  lost  sight  of  the  fact  that  natural 
selection  in  no  way  sufficed  to  explain  phylogenetic  evolu- 
tion completely,  and  he  was  always  convinced  that 
non-inheritance  was  irreconcilable  with  the  fundamental 
biogenetic  law  that  ontogeny  is  only  a  recapitulation  of 
phylogeny.  This  law,  whose  remote  and  immediate 
consequences  constantly  stimulated  the  reflection  of  the 
author,  has  finally  led  him  in  a  purely  inductive  way  to 
the  new  biogenetic  hypothesis  about  to  be  presented. 

It  seemed  to  the  author  that  he  ought  to  devote  a 
special  effort  to  the  elaboration  and  exposition  of  this 
hypothesis,  for  he  saw  from  the  outset  that  it  promised 
an  explanation  not  only  for  the  inheritance  of  acquired 
characters  but  also,  and  quite  independently,  for  a  whole 
series  of  fundamental  biological  phenomena,  and  how  it 
afforded  an  outlet  from  the  blind  alley  into  which  onto- 
genetic  biology  seems  to  have  run:  for  while  some  facts 
lead  us  to  reject  epigenesis  as  it  is  commonly  understood, 
others  force  us  to  reject  pre formation,  and  similarly 
while  a  whole  series  of  reasons  force  us  to  hold  as 
inadmissable  a  homogeneous  germinal  substance  or  a  sub- 
stance only  chemically  heterogeneous,  another  whole 
series  of  reasons  obliges  us  to  hold  no  less  inadmissable  a 
germinal  substance  constituted  by  the  germs  of  the 
preformists. 

The  author  knows  well  that  he  must  not  entertain  any 
oversanguine  expectations.  In  the  position  of  biological 
science  today  we  can  deal  only  with  preliminary  hypoth- 
eses, of  which  each  gives  way  to  its  successor  and  each, 
taking  in  a  greater  number  of  phenomena  than  its  pred- 
ecessor prepares  the  way  for  a  later  hypothesis  which 


Introduction  7 

is  able  in  its  turn  to  include  a  number  greater  still.  So 
soon  as  a  hypothesis  pushes  a  bit  nearer  to  the  beleaguered 
fortress,  so  to  speak,  and  indicates  new  lines  for  study, 
observation  and  research,  one  must  admit  that  it  has  ful- 
filled its  purpose.  And  this  applies  to  our  view  of  the  new 
biogenetic  hypothesis  which  we  here  submit  to  the  judg- 
ment of  biologists  and  of  positive  philosophers  in  general. 

We  have  believed  it  expedient  to  follow  in  the  exposi- 
tion of  this  theory  the  order  in  which  it  was  conceived 
and  built  up,  and  so  the  first  chapter  describes  briefly  the 
inductive  way  in  which  the  author,  starting  out  from  the 
fundamental  biogenetic  law,  was  led  to  the  conception  of 
his  hypothesis.  In  the  three  following  chapters  are  col- 
lected and  arranged  as  concisely  as  possible  the  principal, 
different,  biogenetic  facts  which,  quite  independently  of 
the  ever  controverted  question  of  the  inheritance  of 
acquired  characters,  serve  best  to  set  forth  and  define  the 
new  hypothesis  and  which,  since  they  find  in  it  their  most 
complete  explanation,  confirm  it  again  directly  or  in- 
directly in  a  deductive  way. 

After  having  then  undertaken  in  the  fifth  chapter  a 
brief  examination  of  the  question  of  the  inheritance  or 
the  non-inheritance  of  acquired  characters  which  until 
then  we  had  laid  entirely  aside,  we  pass  in  the  sixth 
chapter  to  the  critical  exposition  of  the  principal  biogene- 
tic theories  which  are  current  at  present.  And  we  do  this 
not  only  with  the  object  of  showing  their  inadequacy  to 
explain  the  mechanism  of  inheritance,  but  rather  in 
order  that  the  perception  of  the  reason  of  this  inadequacy 
may  aid  us  in  discovering  the  necessary  and  sufficient  con- 
ditions required  in  any  theory  which  seeks  to  explain  this 
inheritance.  After  that  we  go  on  again  in  the  seventh 
chapter  with  the  examination  of  our  hypothesis  whose 


8  Introduction 

conception  and  elaboration  up  till  then  was  considered 
quite  independently  of  the  question  of  the  possibility  or 
impossibility  of  the  inheritance  of  acquired  characters, 
but  which  supported  by  an  elementary  hypothetical 
phenomenon,  which  in  certain  respects  finds  its  counter- 
part in  the  inorganic  world,  becomes  recognizable  at  once 
as  a  most  complete  explanation  of  this  inheritance. 

Finally  in  the  last  chapter  we  endeavor  to  show  how 
this  elementary  hypothetical  phenomenon  on  which  the 
new  biogenetic  theory  rests,  explains  also  a  fundamental, 
psychic  phenomenon,  to  wit,  memory  and  indeed  the  most 
characteristic  properties  of  the  vital  phenomenon  in  gen- 
eral. And  so  this  elementary  hypothetical  phenomenon 
seems  to  us  capable  of  bringing  together  within  it  and 
referring  to  one  basis  not  only  the  whole  group  of  genetic 
phenomena,  but  all  vital  phenomena  whatever  in  the  very 
widest  sense  of  the  word. 

Since,  for  the  reasons  above  stated,  the  inheritance  of 
acquired  characters  is  a  question  affecting  positive  philos- 
ophy in  the  Comtian  sense  or  scientific  philosophy,  the 
author  ventures  to  hope  that  biologists  and  naturalists 
may  not  regard  him  as  an  unbidden  intruder  into  their 
domain,  but  rather  since  he  is  the  first  to  recognize  the 
many  gaps  and  shortcomings  of  his  work,  he  ventures  to 
hope  that  he  may  count  upon  especial  consideration,  be- 
cause of  the  great  difficulties  with  which  he  who  is  no 
specialist  has  had  to  contend  in  studies  of  so  difficult  a 
nature. 

Milan,  May,  1905.  E.  R. 


ONTOGENY 


CHAPTER  ONE 

ONTOGENY,  AS  A  RECAPITULATION  OF  PHYLOGENY,  SUG- 
GESTS THE  IDEA  OF  A  CONTINUOUS  ACTION  EXERTED 
BY  THE  GERM  SUBSTANCE  UPON  THE  SOMA  THROUGH- 
OUT THE  WHOLE  OF  DEVELOPMENT. 

Everyone  knows  the  fundamental  biogenetic  law  of 
Haeckel :  ontogeny  is  a  recapitulation  of  phylogeny,  that 
is,  the  development  of  the  individual  is  a  rapid  resume  of 
the  development  of  the  species,  a  short  reproduction  of 
the  endless  chain  of  its  ancestors. 

The  most  important  facts  establishing  this  law,  now 
perhaps  irrefutably,  are  so  well  known  that  we  hardly 
need  to  mention  them  here;  for  example:  solipedation 
develops  gradually  in  the  horse  and  only  in  the  last  stages 
of  its  development ;  many  whales  which  later  instead  of 
teeth  have  the  so  called  whalebone  have  teeth  in  their  jaws 
while  they  are  still  in  a  fetal  condition  and  cannot  take 
any  nourishment ;  the  serpent  while  it  is  in  the  embryonic 
state  possesses  its  two  pair  of  limbs,  and  so  on. 

"The  development  of  the  organism,"  writes  Roux,  "is 
not  merely  a  production  of  the  complex  from  the  simple 
by  the  most  direct  route.  The  ways  are  devious;  and 
many  a  forward  step  must  be  retraced.  We  mention  only 
the  well  known  examples  of  the  gill  clefts  and  gill  arteries 
and  their  ultimate  concrescence,  the  notochord  also,  and 
the  pituitary  and  pineal  glands,  structures  quite  super- 

ii 


12  Biogenetic  Law  of  Recapitulation 

fluous  and  functionless  from  the  first."  l  Development 
of  this  sort,  proceeding  toward  its  goal  not  by  the  direct 
line  but  by  byways  and  often  backwards,  would  be  incom- 
prehensible were  it  not  for  the  fundamental  biogenetic 
law. 

Also  Delage  draws  attention  to  the  fact  that  all  those 
structures  which  disappear  during  the  progress  of 
development  must  nevertheless  have  their  significance.2 

Similarly  Oscar  Hertwig  notes  expressly  that  there 
exist  many  embryonal  organs  "which  never  come  into  a 
position  to  perform  the  function  which  they  have  once 
performed  during  the  course  of  phylogeny."  3 

We  must  then  regard  this  fundamental  biogenetic  law 
as  true.  We  can  even  suppose  it  to  be  a  close  approxima- 
tion, that  ontogeny  represents  phylogeny  exactly. 

It  is  true  that  during  the  first  ontogenetic  stages 
phylogeny  is  only  epitomized,  but  this  becomes  steadily 
less  true  the  farther  development  proceeds,  and  during  the 
later  stages  ontogeny  can  be  regarded  as  an  almost  exact 
repetition  of  all  the  corresponding  phylogenetic  stages. 

The  human  embryo,  on  account  of  the  more  numerous 
and  careful  researches  of  which  it  has  been  the  object, 
serves  better  than  any  other  to  illustrate  this  almost  exact 
phylogenetic  repetition  in  the  later  stages.  Its  develop- 
ment demonstrates  even  to  the  smallest  details  how  the 
embryo  passes  through  the  whole  series  of  forms  of  the 
pithecanthropoids,  its  immediate  ancestors.  Thus  for 
example  the  articulations  of  the  leg  in  man  show  during 

1Wilhelm  Roux:  Der  Kampf  der  Teile  im  Organismus.  Leipzig, 
Engelmann,  1881.  P.  59. 

2Delage:  L'heredite  et  les  grands  problemes  de  la  biologic 
generate.  Paris,  Schleicher,  1903.  P.  176. 

'Oscar  Hertwig:  Die  Zelle  und  die  Gewebe.  Zwcites  Buch. 
Jena,  Fischer,  1898.  P.  232. 


Significance  of  This  Law  13 

fetal  life  a  much  closer  resemblance  to  those  of  anthro- 
poids than  during  adult  life.  At  a  certain  stage  of 
development  the  great  toe  instead  of  being  parallel  to  the 
others  forms  an  angle  with  their  direction  as  in  the  apes. 
In  the  same  way  many  of  the  bones  of  the  foot  of  the 
newborn  infant,  in  their  form,  in  their  respective  angles 
of  inclination,  etc.,  resemble  very  closely  those  of  the 
climbing  foot  of  the  anthropoid  apes,  particularly  of  the 
gorilla. 

In  the  attempt  to  see  what  significance  the  funda- 
mental biogenetic  law  can  have  for  the  biologist  we  can 
come  somewhat  nearer  to  the  question  by  supposing 
ontogeny  to  be  an  exact  repetition  of  phylogeny  instead 
of  a  rapid  resume  of  it.  It  is  true  that  it  will  be  necessary 
later  to  make  some  important  corrections  in  this  first  ap- 
proximation and  to  study  the  significance  or  cause  of  the 
abbreviation  and  suppression  in  ontogeny  of  many  phylo- 
genetic  stages ;  and  this  more  intimate  study  will  allow  us 
to  penetrate  further  into  the  innermost  nature  of  the 
phenomenon.  But  for  the  present  we  desire  by  this  tenta- 
tive supposition  that  ontogeny  is  an  exact  repetition  of 
phylogeny,  to  have  the  great  advantage  of  defining  the 
phenomenon  to  be  studied  more  simply  and  precisely,  and 
of  making  our  comprehension  of  it  correspondingly  easier. 
It  is  by  this  means,  that  is  by  successive  degrees  of 
gradual  approximation  that  mechanical,  physical,  and 
chemical  researches  have  usually  proceeded. 

This  first  degree  of  approximation  of  the  fundamental 
biogenetic  law  will  permit  us  then  to  make  the  two  fol- 
lowing statements :  Each  stage  of  the  ontogenetic  devel- 
opment of  any  organism  represents  exactly  one  species 
among  the  ancestors  of  that  organism.  Two  species  hav- 
ing a  common  ancestor  have  an  identical  ontogenetic 


14  Bio  gene  tic  Law  of  Recapitulation 

development  up  to  the  stage  corresponding  to  that  com- 
mon ancestor;  they  do  not  commence  to  diverge  until 
they  have  passed  that  stage. 

But  since  all  the  various  theories  of  heredity  admit 
that  two  distinct  species  descending  from  a  common  re- 
mote ancestor  possess  germinal  substances  different  from 
each  other,  the  question  at  once  presents  itself:  If  these 
germinal  substances  are  different,  how  then  is  it  possible 
that  throughout  a  long  series  of  stages  up  to  the  stage 
corresponding  to  the  common  ancestor  they  present  like 
ontogenetic  forms,  the  very  same  as  those  through  which 
the  ancestor  passed?  If  the  germinal  substance  of  one 
species  is  different  from  that  of  the  other  should  they  not 
from  the  very  beginning  show  a  totally  unlike  series  of 
forms  ? 

A  germinal  substance  in  process  of  development  con- 
stitutes to  a  certain  extent  a  dynamic  system  of  forces  in 
continual  transformation.  But  two  systems  commencing 
to  give  rise  to  two  series  of  successive  transformations 
which  throughout  a  long  time  are  quite  alike  must  neces- 
sarily be  themselves  alike.  And  if  at  a  given  moment  one 
series  diverges  from  the  other  it  is  necessary  to  attribute 
this  divergence  to  one  of  two  causes;  either  to  some  ex- 
ternal circumstance  acting  at  that  moment,  or  to  some 
internal  impulse  becoming  active  just  at  that  moment. 

"The  parallelism  in  the  phenomena  of  ontogeny  and 
phylogeny,"  says  Delage,  "shows  that  first  something 
develops  which  is  similar  to  what  was  developed  in  the 
ancestors,  and  that  then  something  which  remained  till 
then  inactive  is  added  and  development  proceeds 
further."  4 

*Delage:  L'heredite  etc.,  P.  457. 


Succession  of  Ontogenetic  Stages  15 

In  other  words  the  biogenetic  law  implies  that  up  to 
each  stage  of  development  the  productive  cause  of  develop- 
ment remains  the  same  as  that  which  produced  the 
ancestral  species  corresponding  to  that  stage. 

We  should  next  ascertain  whether  the  new  circum- 
stance now  added  or  the  new  force  becoming  active  only 
at  this  stage  and  causing  the  subsequent  development  is 
to  be  sought  for  within  or  without  the  various  parts  of 
the  organism  which  are  actually  in  process  of  formation. 

If  at  the  start  we  limit  ourselves  for  the  sake  of 
simplicity  to  the  consideration  of  morphological  trans- 
formations only,  each  stage  of  development  whether 
ontogenetic  or  phylogenetic  will  appear  to  us  only  as  a 
special  mode  of  distribution  of  the  organic  substance  con- 
stituting the  organism.  But  this  distribution  is  modified 
during  the  life  of  the  adult  individual  only  by  new  func- 
tional stimuli,  that  is  to  say,  only  by  agents  which  are 
external  to  the  structure  in  progress  of  modification.  In 
other  words  the  impulse  by  which  the  corresponding  por- 
tion of  living  organic  substance  is  constrained  to 
distribute  itself  differently  does  not  reside  within  this 
portion  but  comes  to  it  from  without. 

Until  the  contrary  is  proven  we  may  accept  the  state- 
ment that  the  properties  of  living  organic  substance  dur- 
ing development  are  not  different  essentially  from  those 
which  it  presents  when  development  is  completed.  Con- 
sequently when  any  particular  mode  of  distribution  of 
the  organic  substance  becomes  altered  during  the  prog- 
ress from  one  given  ontogenetic  stage  to  the  succeeding 
stage,  we  can  admit  as  a  provisional  hypothesis  that  this 
different  distribution  is  effected  by  some  provocation 
external  to  the  parts  which  change. 

This  provocation  cannot  be  constituted  merely  by  the 


1 6  Biogenetic  Law  of  Recapitulation 

morphological  and  physiological  state  of  the  other  part  of 
the  organism  at  that  moment;  for  in  the  corresponding 
phylogenetic  state  the  two  portions  were  in  perfect 
equilibrium  with  each  other.  It  is  necessary  then  to  sup- 
pose that  somewhere  in  the  remaining  parts  of  the  or- 
ganism, there  enters  into  play  just  at  that  moment  and 
only  at  that  moment,  some  factor  which  was  not  present 
in  the  ancestral  species. 

Further,  since  the  alteration  in  the  organism  during 
ontogeny  is  not  confined  to  a  single  part  of  the  organism 
but  affects  several  parts  at  the  same  time,  and  since  the 
impulse  which  comes  into  play  at  the  end  of  each  stage  of 
development  compelling  the  passage  to  the  successive 
stage  must  lie  external  to  each  of  the  parts  undergoing 
transformation,  it  cannot  lie  in  any  of  these  parts. 

This  will  be  possible,  however,  only  on  condition  that 
among  all  the  different  parts  of  the  organism  there  is  at 
least  one  part  which  is  not  itself  subject  to  any  substantial 
change,  but  in  which  there  comes  into  activity  a  series  of 
specific  energies  one  after  another  of  which  each  provokes 
the  passage  of  all  the  other  parts  of  the  organism  to  the 
next  ontogenetic  stage. 

This  special  part  may  be  called  the  central  zone  of 
development.  And  one  can  give  the  name  of  centro- 
epigenesis  to  this  hypothesis  by  which  ontogenetic 
development  is  made  to  depend  on  an  infinite  number  of 
different  influences  which  this  zone  gradually  exerts  upon 
all  the  remainder  of  the  organism  by  activating  succes- 
sively a  regular  series  of  specific  energies,  each  remain- 
ing in  a  potential  state  up  to  the  time  of  its  activation. 

Now  the  part  which  actually  does  remain  unaltered 
from  the  first  segmentation  of  the  egg  up  to  the  giving  off 
of  the  reproductive  cells  by  the  new  organism  is  the 


Centroepigenesis  vs.  Pre formation  and  Epigenesis    17 

germinal  substance,  and  one  suspects  at  once  that  it  may 
be  just  this  substance  which  constitutes  the  central  zone. 

If  so  it  would  follow  that  the  central  zone  must  be  at 
the  same  time  the  germinative  zone,  that  is  to  say,  the 
place  whence  the  sexual  cells  get  the  germinal  substance 
which  makes  them  capable  of  reproduction.  Let  us 
hasten  to  add  now  that  the  central  zone  must  coincide 
with  the  effective  germinal  zone,  but  may  possibly  be  quite 
separate  and  distinct  from  the  apparent  germinal  zone. 
The  latter  would  be  then  only  the  place  of  formation  of 
the  sexual  cells,  inasmuch  as  these  constitute  in  a  certain 
sense  the  mere  envelope  in  which  later  the  germinal  sub- 
stance is  assembled,  which  alone  is  able  to  give  them 
reproductive  capacity. 

The  hypothesis  of  centroepigenesis  includes  then  that 
of  a  continuous  action  exercised  by  the  germinal  sub- 
stance upon  the  soma  throughout  the  whole  duration  of 
its  development.  We  shall  endeavor  in  the  second  chapter 
to  learn  what  is  the  nature  of  this  action  and  we  shall 
reserve  for  consideration  in  the  third  chapter  the  central 
zone  itself,  as  well  as  other  facts  and  arguments  which 
make  its  existence  seem  probable  and  which  serve  to  make 
the  hypothesis  clearer. 

We  shall  limit  ourselves  here  to  putting  in  special  light 
the  fundamental  characteristics  which  differentiate  this 
hypothesis  as  well  from  the  preformistic  as  from  the 
epigenetic  theories. 

While  Weismann  and  the  preformists  in  general  con- 
sider that  the  germ  plasm  separates  itself  before  the  com- 
mencement of  development  from  the  portion  set  apart  to 
form  the  new  organism,  and  remains  passively  aside  in  a 
detached  part  of  the  soma  until  it  later  steps  in  to  form 
the  future  sexual  cells;  consequently  it  would  not  control 


1 8  Bio  genetic  Law  of  Recapitulation 

development  nor  indeed  have  any  part  whatever  in  it; 
that  would  fall  entirely  to  the  other  portion  alone,  and  it 
would  be  just  this  passivity  which  would  secure  the  in- 
alterability of  the  germ  plasm : 

While  on  the  other  hand  the  epigenesists  consider  that 
the  idioplasm  would  participate  in  an  important  and  con- 
tinuous way  in  development,  because  it  would  be  present 
and  active  at  every  instant  and  in  all  cells;  it  would 
remain,  however,  in  spite  of  this  participation  permanently 
unaltered,  so  that  the  cells  of  the  soma  would  never  be- 
come differentiated  by  nuclear  somatization  from  the 
germ  cells,  but  on  the  contrary  retain  the  capacity  of 
reproduction  to  the  same  extent : 

The  centroepigenetic  hypothesis  postulates  on  the  con- 
trary that  the  germinal  substance,  although  limited  to  a 
single  zone  and  separated  and  differentiated  from  the  rest 
of  the  soma,  nevertheless  exercises  its  epigenetic,  forma- 
tive action  upon  all  the  rest  of  the  organism  and  during 
the  whole  of  development,  without  undergoing  any  altera- 
tion whatever  through  this  participation  in  development. 

But  this  hypothesis  thus  sketched  must  now  be  made 
more  precise  and  clear  by  the  consideration  of  other  series 
of  phenomena,  while  at  the  same  time  the  proof  of  the 
facts  is  undertaken.  And  to  this  we  propose  to  proceed 
in  the  chapters  which  follow. 


CHAPTER  TWO 

PHENOMENA  WHICH  INDICATE  A  CONTINUOUS  FORMA- 
TIVE ACTION  WHICH  IS  EXERTED  BY  PARTS  OF  THE 
SOMA  UPON  THE  OTHER  PARTS  THROUGHOUT  THE 

WHOLE      OF      DEVELOPMENT HYPOTHESIS      OF      THE 

NATURE  OF  THE  FORMATIVE  ACTION. 

i.     Phenomena  Which  Indicate  a  Continued  Formative 

Action 

Among  the  phenomena  which  seem  to  indicate  indis- 
putably a  continuous  formative  action  exercised  by  a 
more  or  less  great  part  of  the  soma  upon  the  other  parts 
throughout  the  whole  of  development,  those  of  the  re- 
generation of  amputated  organs  take  a  first  place. 

It  is  known  that  when  the  antennae  of  a  snail,  the 
chelae  of  a  crab,  the  feet  of  a  salamander  or  the  head  of 
a  worm  are  amputated,  these  organs  are  reproduced  even 
when  the  amputation  is  performed  during  adult  life. 

Spallanzani  has  cut  the  feet  and  tail  off  the  same  sala- 
mander six  successive  times,  and  Bonnett  seven  times, 
and  each  time  feet  were  reproduced  of  exactly  the  same 
size  as  the  former  ones  without  any  increase  or  decrease 
in  any  part.  These  facts  show  that  the  formative  agent 
whatever  it  may  be  is  always  external  to  the  part  formed, 
and  that  it  exercises  upon  the  whole  development  of  that 
part  and  throughout  its  entire  duration  a  continuous  ac- 
tion, and  further  that  it  remains  itself  unaltered  even 

19 


20     Indications  of  Continued  Formative  Influence 

after  the  completion  of  its  work  and  consequently  is  ca- 
pable of  renewing  it  at  every  favorable  opportunity. 

If  on  account  of  unusual  conditions  the  regeneration 
of  the  amputated  part  proceeds  in  an  abnormal  fashion, 
the  remaining  part  continues  always  in  spite  of  that  to  be 
capable  of  normal  regeneration.  For  example :  an  axolotl 
had  a  foot  bitten  off.  The  foot  was  reproduced  but  badly 
formed.  This  foot  was  amputated  and  a  third  was 
developed  which  was  quite  normal.5 

We  shall  later  at  a  proper  place  treat  of  the  ill-starred 
attempts  of  the  preformists  to  bring  their  theory  into 
accord  with  similar  phenomena,  and  of  the  arguments 
and  the  special  regenerative  processes  which  the  epigene- 
sists  have  brought  forward  in  support  of  their  theory. 
Here  it  may  merely  be  noted  that  while  epigenetic  theories 
furnish  an  immediate  explanation  for  all  phenomena  of 
regeneration,  the  pre  formation  theory  on  the  contrary 
must  have  recourse  to  the  addition  of  complicated  sub- 
sidiary hypotheses  which  are  entirely  opposed  to  the 
principal  one. 

If  the  morphological  capacity  does  not  reside  in  the 
somatic  cells  of  the  cut  surface,  which  by  their  multiplica- 
tion produce  the  regenerated  organ,  but  is  outside  these, 
it  follows  that  the  continuous  action  exercised  upon  all 
cells  at  the  end  of  the  regenerated  part  as  also  upon  all 
cells  which  do  not  lie  at  the  cut  surface,  by  the  remaining 
part  of  the  organism  must  be  a  mediate  action  exercised 
from  a  distance,  and  therefore  must  traverse  intermediate 
cells. 

A  yet  more  striking  demonstration  of  a  continued, 

BDarwin:  The  variation  of  animals  and  plants  under  domestica- 
tion. Eighth  impression  of  the  second  edition.  London,  Murray. 
1899.  P.  357,  358. 


Mediate  Formative  Influence  in  Post-generation   21 

formative  action  exercised  mediately  and  at  a  distance  by 
one  part  of  the  organism  upon  another  during  the  entire 
development  of  this  latter  is  furnished  by  the  famous  ex- 
periments of  Roux  in  the  post-generation  of  his  half 
embryos. 

The  words  in  which  he  describes  the  process  of  this 
post-generation  which  he  has  observed  in  half  embryos 
obtained  from  frogs'  eggs  after  he  had  killed  one  of  the 
first  two  blastomeres  with  a  hot  needle,  deserve  to  be 
reproduced  here  in  full. 

But  we  must  remember  at  the  outset  that  while  the 
uninjured  blastomere  develops  into  only  a  half  embryo, 
the  injured  blastomere  lying  beside  its  neighbor  produces 
often  a  late  fragmentation  of  its  protoplasmic  mass  con- 
sisting only  of  undifferentiated  cells.  And  this  is  effected 
in  one  of  the  following  two  ways,  either  through  only 
partial  killing  of  the  nucleus  concerned  some  individual 
fragments  of  it  continuing  to  live  and  multiply,  or 
through  an  emigration  of  naked  nuclei  from  the  part  of 
the  egg  remaining  intact  into  the  protoplasm  of  the  in- 
jured blastomere.  Now  we  quote  Roux. 

"Postgeneration  of  germ  layers  of  half  organisms 
proceeds  always  from  the  already  differentiated  germ 
layers  of  the  normally  developed  half  of  the  egg.  It 
extends  thence  first  to  the  yolk  mass  subsequently  cel- 
lulized,  especially  where  such  a  germinal  layer  is  in  con- 
tact with  such  a  mass  by  a  broken  surface  and  conse- 
quently by  the  lateral  surfaces  of  its  cells." 

"The  formation  commencing  at  this  point  proceeds 
steadily  and  continuously  through  the  yolk  mass  of  the 
undeveloped  half  of  the  egg.  About  the  free  margin  of 
the  advancing  germinal  differentiation  there  are  to  be 
found  gradual  transition  stages  between  the  undiffer- 


22     Indications  of  Continued  Formative  Influence 

entiated  yolk  cells  and  the  cells  of  the  already  completely 
differentiated  germinal  layer.  With  the  elimination  of 
other  possibilities  this  leads  us  to  the  conclusion  that  the 
progressive  differentiation  is  accomplished  in  material 
already  in  position  before  differentiation  commenced,  and 
remaining  there  throughout  it,  and  therefore  in  passive 
yolk  material  by  direct  transformation  of  the  yolk  cells 
(accompanied  in  the  case  of  the  ectoderm  and  mesoderm 
also  by  the  division  of  these  cells)." 

"As  to  the  location  of  the  causes  of  these  processes," 
continues  Roux,  "we  can  draw  a  few  further  conclusions." 

"Since  the  yolk  cell  material  later  differentiated  to  form 
the  germ  layers  in  the  manner  described  above  has  been 
quite  disordered  in  its  substance  forming  the  bodies  of  the 
cells,  by  the  operation,  and  since  also  the  nuclear  material 
of  the  cells  which  are  later  formed  from  it  has  never 
yet  taken  its  place  by  virtue  of  a  typical  division,  but,  being 
derived  partly  from  the  nucleus  of  the  half  operated  upon 
and  partly  from  the  emigrated  naked  nuclei  of  the  half 
remaining  intact,  owes  its  disposition  to  the  chance  of 
the  moment,  therefore  the  conception,  possible  in  the 
case  of  normal  development  that  at  typical  places  there 
is  always  deposited  typical  material  capable  of  quite 
definite  independent  development,  cannot  be  admitted  in 
this  case." 

"We  must  conclude  rather,  that  the  cause  of  this  typ- 
ical formation  of  the  germ  layers  of  the  first  developed 
half  of  the  egg,  extending  into  the  half  operated  upon,  lies 
in  forces  which  proceed  from  the  germ  layers  of  the  first 
half." 

"I  conclude,  then,  that  in  our  postgeneration  the 
progressive  differentiation  extends  in  space  as  the  result 
of  a  direct  assimilating  and  differentiating  action  exercised 


Continuous  Formative  Influence  23 

by  differentiated  cells  upon  other  less  differentiated  cells 
which  are  immediately  adjacent  to  them." 

"In  the  latter  process  very  different  degrees  of  action 
are  possible.  There  can,  for  example,  emanate  from  the 
differentiated  cells  an  influence  which  simply  sets  free 
the  process  of  differentiation  allowing  the  entire  series 
of  necessary  changes  after  this  preliminary  impulse  to 
proceed  of  itself.  Or,  each  of  these  changes  may  not 
merely  receive  from  the  differentiated  cell  a  simple 
initial  impulse,  but  may  on  the  contrary  be  determined 
by  that  throughout.  Between  these  two  extremes  one 
can  imagine  a  whole  series  of  intermediate  stages.  On 
account  of  the  at  first  atypical  disposition  of  the  material 
which  at  last  becomes  typically  differentiated  I  am 
inclined  to  think  that  the  action  of  the  differentiated  cells 
upon  the  nondifferentiated  cells  is  not  a  mere  liberating 
one  or  a  mere  stimulating  one."  G 

These  facts  of  postgeneration  indicate  then  above  all 
that  the  action  of  the  half  embryo  already  formed  upon 
the  other  half  in  process  of  formation  is  exercised  in  a 
continuous  manner  throughout  the  whole  development 
of  this  latter. 

One  would  be  led  also  to  this  conclusion,  that  there 
is  a  continuous  action  exercised  throughout  the  whole  of 
development,  by  the  fact  that  the  postgeneration  of  the 
undeveloped  half  goes  on  with  greater  rapidity,  so  that 
it  soon  overtakes  the  other  half  and  proceeds  with  it  to 
the  same  stage  of  development. 

"Wilhelm  Roux :  Uber  die  kiinstliche  Hervorbringung  ,,halber" 
Embryonen  durch  Zerstorung  einer  der  beiden  ersten  Furchungszellen, 
sowie  uber  die  Nachentwicklung,  Postgeneration  der  fehlenden 
Korperhalfte.  Virchows  Archiv,  Bd.  114.  October  1888,  P.  279 — 282. 
Gesamm.  Abhandl.,  Zw.  Band.  P.  507 — 509. 


24     Indications  of  Continued  Formative  Influence 

This  continued  action  leads  us  to  conclude  also  that  as 
a  further  consequence  a  remote  action  is  exercised  by 
the  half  embryo  already  formed  upon  the  parts  of  the 
other  half  which  are  not  in  direct  contact  with  the  first. 
This  remote  action  can  be  transmitted  only  through  all 
the  intermediate  cell  layers  which  lie  between  the  surface 
of  contact  of  the  two  half  embryos  and  the  remote  parts 
in  process  of  postgeneration. 

It  would  seem  necessary  then  to  conclude  that  the  first 
half  embryo  exercises  upon  the  far  removed  parts  of  the 
second  a  remote,  mediate  and  continuous  action. 

We  shall  now  provisionally  assume  that  postgenera- 
tion does  not  differ  in  its  essential  nature  from  direct  gen- 
eration, and  note  some  consequences  which  follow  for 
the  hypothesis  of  the  central  zone  of  development  which 
during  normal  ontogenesis  would  exert  an  action  similar 
to  that  which  the  half  of  the  embryo  already  formed 
exerts  upon  the  other  half  during  postgeneration. 

The  nuclei  obtained  as  the  result  of  the  first  divisions 
of  the  egg  and  destined  to  become  somatic,  even  though 
derived  from  those  which  according  to  this  hypothesis 
\vould  later  form  the  central  zone,  would  then  have  to  be 
considered,  in  relation  to  the  somatizing  stimulus  exerted 
by  that  zone,  as  quite  like  the  indifferent  nuclei  of  the 
embryonal  half  capable  of  post  generation,  which  receive 
now  this  now  that  stimulus  without  any  preference  from 
the  half  already  developed,  and  become  somatized  in 
consequence  now  in  one  way  now  in  another  way 
according  as  they  may  chance  to  be  disposed. 

The  indifference  in  respect  to  somatizing  stimuli  of 
these  nuclei,  which  we  should  at  least  at  the  outset 
suppose  like  those  nuclei  from  which  they  are  derived, 
and  which  later  according  to  this  hypothesis  give  rise 


Elastomer es  Which  Acquire  Formative  Control    25 

to  the  effective  germinal  zone,  leads  us  to  a  second 
hypothesis,  namely:  that  the  especially  germinative 
energies  of  those  nuclei  destined  to  become  somatic  may 
be  once  for  all  silenced,  that  is  once  for  all  put  in  a 
potential  state  incapable  of  activation,  on  account  of  the 
preponderance  which  the  nuclei  that  go  to  form  the 
effective  germinal  zone  or  central  zone  acquire. 

In  fact  we  can  suppose  that  the  first  blastomeric  nuclei, 
though  exactly  alike  qualitatively,  are  different  quanti- 
tatively, that  is  to  say  are  furnished  with  amounts  of 
energy  which  do  not  chance  to  be  quite  the  same  in  all, 
perhaps  on  account  of  special  conditions  of  nutrition  or, 
perhaps,  on  account  of  special  conditions  of  the  proto- 
plasm in  which  they  are  placed.  Then,  as  soon  as  the 
moment  comes  when  because  of  the  nature  of  the  com- 
mencing transformation,  such  as  perhaps  imagination  or 
some  such  thing,  embryonal  development  can  no  longer 
proceed  after  the  same  fashion  in  all  cells,  certain  ones 
will  necessarily  gain  the  upper  hand,  namely  those  which 
possess  more  potential  energy. 

The  other  blastomeres  whose  nuclei  would  no  longer 
be  able  to  activate  their  germinal  energies  will  from  now 
on  conduct  themselves,  in  relation  to  the  stimuli  of  the 
nuclei  of  those  blastomeres  which  constitute  the  central 
zone  of  development,  just  like  cells  with  indifferent 
nuclei.  And  with  the  progressive  somatization  of  these 
latter  the  mass  of  their  respective  specific  elements  to 
which  is  due  the  persistence,  potentially  at  least,  of  their 
germinal  energies,  will  gradually  diminish  and  finally 
disappear. 

There  is  only  a  single  conceivable  exception,  namely 
the  case  in  which  at  the  beginning  of  development  or  in 
inferior  forms,  these  blastomeres  or  cells  just  beginning 


26     Indications  of  Continued  Formative  Influence 

to  be  somatized  accidentally  remain  isolated,  in  which 
case  the  activation  of  their  potential  germinal  energies 
would  be  permitted,  which  might  have  been  impossible 
had  they  remained  united  with  the  other  blastomeres  or 
cells. 

The  possiblity  of  such  receptive  indifference  toward 
somatizing  stimuli  in  nuclei  which  if  they  were  isolated 
or  in  other  conditions  would  on  the  contrary  possess  and 
give  practical  demonstration  of  very  definite  specific 
qualities,  is  indicated  by  those  cases  in  which  all  the 
nuclear  material  of  the  post  generated  half  embryo  is 
furnished  by  the  half  already  developed. 

Indeed  it  often  happens  that  on  the  side  operated  upon 
the  nutritive  yolk  alone  is  utilized;  and  into  this  latter 
emigrate  nuclei  formed  by  normal  division  of  the  nuclei 
of  already  somatized  cells  in  the  developed  half  of  the 
egg.  And  these  emigrated  nuclei  then  bring  about  the 
division  of  the  yolk  mass  of  the  part  operated  upon  into 
small  indifferent  cells  only:  "With  the  formation  of  a 
right  or  left  half  embryo,"  Roux  observes  in  a  later 
study,  "the  formative  capacity  of  the  uninjured  half  of 
the  egg  is  not  yet  exhausted.  On  the  contrary  certain 
experimental  results  permit  the  conclusion  that  in  many 
cases  there  is  an  emigration  from  it  of  nuclei,  and 
perhaps  indeed,  of  a  little  protoplasm  also,  going  out 
from  those  points  which  by  the  accident  of  position  have 
the  most  intimate  contact  with  the  side  operated  upon, 
toward  the  contiguous  half  of  the  egg  deprived  of  its 
own  capacity  of  development.  These  nuclei  become 
distributed  throughout  the  whole  of  the  large  mass  of 
yolk  and  thereupon  follows  later  a  breaking  up  of  the 
half  operated  upon  into  cells,  and  this  is  not  as  in  normal 
division  a  division  of  the  whole  mass  first  into  two  nearly 


Cells  Partially  Differentiated  Can  Be  Altered     27 

equal  and  consequently  large  cells,  which  divide  again 
later  in  their  turn  each  into  two  correspondingly  smaller 
cells  and  so  on;  but  on  the  contrary  the  breaking  up  is 
from  the  first  into  small  cells." 

It  is  upon  these  indifferent  cells  that  the  half  of  the 
egg  already  developed  exercises  its  formative  action. 
These  nuclei  which  arise  from  cells  of  the  half  of  the 
embryo  already  developed  must  nevertheless  possess  very 
definite  specific  properties;  some  come  from  ectodermic 
cells,  others  from  mesodermic  and  others  from  entodermic 
cells.  And  if  the  medullary  plate,  the  notochord,  etc., 
have  already  been  formed,  the  vagrant  nuclei  come  also 
from  cells  which  are  in  an  advanced  stage  of  development. 
And  yet  when  they  have  once  emigrated  and  have  become 
scattered  through  the  yolk  of  the  injured  side,  they 
remain  no  less  indifferent  in  relation  to  the  formative 
stimuli  which  come  off  later  from  the  part  already 
formed,  than  in  the  cases  where  they  arise  entirely  from 
the  injured  half  of  the  egg.  From  whatever  cells  of  the 
embryonal  half  already  developed  they  may  have  been 
produced,  they  are  capable  of  any  somatization  whatever, 
for  this  depends  only  on  the  place  at  which  they  happen 
to  stop  or  become  arrested  during  their  migration  into 
the  yolk  plasma  of  the  injured  half  of  the  egg. 

The  same  thing  can  take  place  in  the  blastomeric 
nuclei  also  as  soon  as  they  once  find  themselves  outside 
the  group,  which,  according  to  the  hypothesis  above 
stated,  would  form  the  central  zone  of  development:  in 
relation  to  the  ontogenetic  stimuli  which  from  now  on 

7Wilhelm  Roux:  Uber  das  entwicklungsmechanische  Vermogen 
jeder  der  beiden  ersten  Furchungszellen  des  Eies.  Verhandlungen 
der  anat  Ges.  Wien.  June  1892.  P.  34,  35.  Gesamm.  Abhandl. 
Zw.  Bd.  P.  782,  783. 


28     Indications  of  Continued  Formative  Influence 

are  sent  out  from  this  zone,  they  conduct  themselves  in 
a  quite  indifferent  way,  though  for  a  greater  or  less  time 
they  preserve  their  germinative  capacity  potentially. 

While  the  experiments  of  Roux  carried  on  carefully 
and  with  astonishing  exactness  of  observation,  dem- 
onstrate directly  the  continued  remote  and  mediate  action 
which  the  formative  part  exercises  upon  the  part  being 
formed  throughout  the  whole  of  development,  the  exist- 
ence of  this  action  is  confirmed  by  other  investigations, 
in  a  way  which  though  indirect  is  not  any  less  certain 
on  that  account. 

They  comprise  all  the  cases  in  which  the  part  removed 
is  regenerated  by  cells  histologically  different  from  those 
of  normal  generation,  for  instance  in  which  organs  or 
tissues  of  ectodermic,  mesodermic,  or  entodermic  origin 
are  reproduced  in  the  regeneration  by  tissues  having  a 
different  blastodermic  origin. 

It  will  suffice  for  our  object  to  recall  the  most  typical 
example  which  has  stirred  up  the  two  hostile  camps  of 
the  epigenesists  and  the  preformists;  we  refer  to  that 
of  the  regeneration  of  the  lens  in  the  eye  of  the  tritons, 
which,  after  its  extirpation,  is  reproduced  from  the  cells 
of  the  iris,  that  is  to  say,  from  a  material  quite  different 
in  character  from  that  of  which  it  is  formed  in  normal 
generation.8 

The  double  epithelial  layer  of  the  iris,  from  the 
marginal  proliferation  of  which  the  new  lens  springs, 
must  exercise  upon  the  lens  in  process  of  formation  a 
continuous  action  persisting  throughout  the  development 

8See  e.  g.  Erik  Miiller:  Uber  die  Regeneration  der  Augenlinse 
nach  Exstirpation  derselben  beim  Triton.  Archiv  f.  mikrosk.  Anat. 
und  Entwicklungsgesch.  Band,  XLVII.  erstes  Heft.  Bonn.  Cohen, 
1896.  P.  23  ff.,  especially  29  and  30. 


The  Formative  Stimulus  the  Determining  Factor  29 

of  the  lens.  For  the  cells  of  the  iris  cannot  preserve 
within  them  potentially  any  trace  of  a  formative  capacity, 
or  of  a  germinal  "anlage,"  or  of  any  "determinant"  which 
provokes  the  formation  of  the  lens,  seeing  that  in  normal 
development  the  latter  takes  its  origin  from  another 
tissue. 

In  these  examples,  both  in  the  post  generation  of 
Roux's  half  embryos  and  in  the  regeneration  of  the  lens 
in  the  triton,  the  cells  which  serve  as  constructive 
material  appear  then  to  be  absolutely  incapable  of  any 
auto-transformation  and  ready  on  the  contrary  to  differ- 
entiate themselves  and  to  dispose  themselves  indifferently 
in  any  manner  whatever,  according  to  the  formative 
stimulus  to  which  they  happen  to  be  exposed. 

At  this  point  the  fundamental  biological  question  pre- 
sents itself:  What  is  the  nature  of  these  formative 
stimuli,  of  this  continued  action  which  the  formative  part 
exercises  upon  the  part  being  formed? 

The  attempt  to  build  up  a  hypothesis  relating  to  so 
important  a  question  is  the  object  of  the  studies  presented 
in  the  second  part  of  this  chapter. 

2.     Hypothesis  of  the  Nature  of  the  Formative  Stimulus 

If,  in  our  study  of  the  nature  of  the  formative  stimulus 
in  the  development  of  organisms,  we  start  with  the 
primitive  pluricellular  form,  consisting  simply  of  aggre- 
gations of  cells  that  are  all  alike,  we  observe  that  during 
some  stages  of  their  ontogeny  the  essential  nature  and 
the  behaviour  of  these  cells  is  clearly  determined  by 
phenomena  of  nervous  nature  in  the  widest  sense  of  the 
word.  For  example,  phenomena  of  this  nature  exist 
undoubtedly  in  the  little  mononuclear  amoebae  into  which 
the  spores  of  the  myxomycetes  become  changed,  also  in 


30  Nature  of  the  Formative  Stimulus 

the  zoospores  which  move  about  by  means  of  their 
vibratile  flagella  and  into  which  these  mononuclear 
amoebae  become  transformed.  And  it  is  certain  that 
phenomena  likewise  nervous  in  character  must  come  into 
play  when  the  cells  of  Magosphera  planula  become 
separated  from  one  another  and  each  one  moves  off 
independently  by  means  of  its  cilia. 

One  is  justified  then  in  suspecting  that  when  these 
cells  are  united  in  a  colony  they  may  then  also  be  the 
seat  of  phenomena  of  a  nervous  nature,  and  that  the 
other  ontogenetic  stages  of  these  minute  organisms  ought 
also  to  be  attributed  to  such  phenomena. 

But  then  we  should  have  to  refer  the  development  of 
higher  organisms  also  to  phenomena  of  the  same  nature. 

As  a  support  of  this  hypothesis  we  recall  the  well 
known  fact  that  all  cells  of  organisms,  from  these  most 
primitive  pluricellular  forms  up,  are  united  to  one  another 
by  a  network  of  intercellular  protoplasmic  bridges. 

We  recall  the  example  which  the  different  species  of 
Volvox  afford,  a  genus  of  lower  algae  consisting  of  a 
vesicle  formed  of  a  single  layer  of  cells,  very  much  like 
the  blastula  stage  of  the  development  of  animals.  All 
the  species  of  Volvox  show  a  perfectly  typical  and 
regular  form  of  union  between  the  different  cells  of  the 
body.  In  Volvox  aureus  for  example,  the  superficial 
cells  of  the  trophic  hemisphere  of  the  vesicle  lie  in  a  thick 
soft  gelatinous  mucus  and  each  is  not  only  provided  with 
two  long  flagellae,  but  also  is  connected  with  each  of 
the  five  or  six  adjoining  cells  by  a  long,  thin  protoplasmic 
filament.  In  the  germinal  hemisphere  the  protoplasmic 
filaments  are  more  numerous  so  that  each  of  the  great 
spores  which  arise  there  is  connected  with  each  one  of 
the  large  neighboring  cells  by  bundles  of  from  three  to 


Stimulus  to  Formation  of  Cell  Membranes       31 

six  filaments.  These  protoplasmic  connections  persist 
for  some  time  even  when  the  spores  have  been  divided 
into  two,  four,  or  more  constituent  parts.9 

An  experiment  which  has  already  become  famous 
appears  to  indicate  that  the  intercellular  bridges,  as  if 
they  were  successors  of  the  vibratile  protoplasmic  fila- 
ments, substituted  for  them,  are  traversed  incessantly  by 
nervous  currents  or  discharges  emanating1  from  the 
nucleus.  For  this  experiment  we  are  indebted  to  Pfeffer. 

After  having  detached  by  plasmolysis  the  cell  mem- 
brane of  the  nucleated  protoplasmic  body  of  a  plant  cell, 
and  dividing  the  cell  into  halves,  one  containing  a  nucleus 
and  one  without  any,  he  observed  that  only  the  nucleated 
half  had  surrounded  itself  with  a  new  cell  membrane. 
If  however,  the  part  deprived  of  the  nucleus  remained 
united  to  the  nucleated  fragment  even  by  only  a  very 
fine  protoplasmic  filament,  it  also  was  capable  of  secreting 
its  little  cellulose  membrane. 

Pfeffer  varied  his  experiment  also  in  the  following 
manner.  He  prepared  cells  of  a  moss  protonema  in  such 
a  way  that  an  entirely  isolated,  anucleate  mass  of  proto- 
plasm remained  united  to  the  neighboring  cell  which  con- 
tained a  nucleus  by  means  of  thin  filaments  piercing  the 
cell  wall.  In  this  case  a  membrane  was  formed  round 
the  anucleate  fragment.  But  the  membrane  was  not 
formed  if  the  neighboring  cell  had  been  itself  deprived 
of  its  nucleus. 

In  the  formation  of  this  cellular  membrane  in 
anucleated  parts  of  the  cytoplasm  united  by  protoplasmic 
filaments  with  other  nucleated  portions,  the  maximum 
intervening  distance  observed  by  Pfeffer  was  3.7  mm. 

"Oscar  Hertwig:  Die  Zelle  und  die  Gewebe.  Zw.  Buch,  P.  34, 
35.  Fig.  16,  17. 


32  Nature  of  the  Formative  Stimulus 

"But  the  nucleus  can  certainly  exercise  the  membrane 
forming  stimulus  at  an  even  greater  distance."  If  the 
nucleus  remains  united  with  a  whole  chain  of  anucleated 
bits  of  cytoplasm  "the  production  of  the  membrane  appears 
to  advance  centrifugally  and  so  to  commence  a  little  later 
in  the  more  remote  portions  of  cytoplasm,  than  in  the 
bits  nearer  the  nucleus."  10 

From  these  experiments  one  is  inclined  to  think,  this 
author  concludes,  "that  the  production  of  a  cellular 
membrane  required  the  continuous  transmission  and 
cooperation  of  certain  states  of  motion  and  vibration 
which  radiate  out  from  cell  nuclei  or  rather  owe  their 
origin  to  the  reciprocal  action  of  nucleus  and  cytoplasm." 

Oscar  Hertwig  makes  in  this  connection  the  following 
remark:  "This  experiment  proves  that  the  stimulus 
necessary  for  membrane  formation  can  be  transmitted 
by  thin  connecting  filaments  which  traverse  the  septum 
interposed  between  two  cells.  Nothing  hinders  us  then 
from  assuming  that  some  similar  transmission  goes  on 
in  other  functional  conditions."  n 

In  these  observations  of  Pfeffer  the  formation  of  the 
membrane  goes  on  independently  of  the  situation  and 
remoteness  of  the  nucleus  and  of  the  geometric  form  of 
the  line  of  communication  which  may  be  straight  or 
curved  in  any  way,  and  consequently,  (and  we  must  keep 
this  especially  in  mind,)  just  as  though  this  formation 
were  effected  by  a  specifically  stimulating  current,  passing 

10Pfeffer:  Uber  den  EinflujS  des  Zellkerns  auf  die  Blldung  der 
Zellhaut.  Berichte  liber  die  Verhandl.  der  konigl.  sachs.  Gesellsch. 
d.  Wissensch.  zu  Leipzig.  1897.  P.  507. 

"Oscar  Hertwig:  Die  Zelle  und  die  Gewebe.  Zw.  Buch,  P. 
40,  41. 


Currents  of  Nervous  Energy  in  Skin  Cells       33 

out  from  the  nucleus  and  quite  independent  of  the  form 
and  extent  of  the  conductor  which  carries  it. 

But  it  is  very  probable  that  this  nervous  current  or 
discharge  which  is  conducted  from  the  nucleated  cell 
along  the  protoplasmic  filaments  to  the  anucleated  frag- 
ment of  the  contiguous  cell,  also  passes  across  into  the 
fragment  even  when  it  contains  a  nucleus  and  so  also 
when  it  is  replaced  by  an  entire  cell.  This  leads  us  to 
the  conception  that  wherever  intercellular  protoplasmic 
connections  are  present,  the  various  nuclear  currents  or 
discharges  stream  through  these  connections  and  so 
permit  a  general  nervous  flux  throughout  the  whole  net- 
work of  these  protoplasmic  bridges,  in  the  meshes  of 
which  the  nuclei  themselves  would  constitute  the  nodal 
points.  In  this  way  one  would  have  a  continuous 
circulation  or  distribution  of  nervous  energy  throughout 
the  entire  organism. 

This  supposition  is  supported  by  the  experiments  of 
Siegfried  Garten.  On  his  own  arm  he  cut  out  a  little 
disc  of  skin  one  centimeter  in  diameter  so  as  to  lay  bare 
the  muscle  fibers.  Without  suturing  the  wound  he 
covered  it  with  an  aseptic  dressing  and  left  it  to  the 
process  of  granulation.  After  the  wound  was  completely 
covered  with  epithelium  except  only  a  small  circle  of 
1.75  mm.  radius  he  cut  out  the  whole  piece  again  and 
enough  around  it  to  reach  to  the  area  in  which  the 
skin  was  in  quite  normal  condition. 

Microscopic  observation  gave  the  following  result: 
Studying  it  from  the  center  of  the  wound  out,  one  met 
first  of  all  a  greater  or  less  number  of  wedge  shaped 
epithelial  cells  with  the  long  axes  radially  disposed. 
Surrounding  this  came  next  an  annular  zone,  0.45  mm. 
broad,  of  fusiform  epithelial  cells  whose  long  axes  were 


34  Nature  of  the  Formative  Stimulus 

almost  without  exception  tangentially  disposed,  that  is 
perpendicularly  to  the  radius  of  the  wound,  and  the 
protoplasmic  filaments  within  the  cells  ran  parallel  with 
their  axes.  In  correspondence  with  this  interior  cellular 
arrangement,  the  intercellular  bridges  into  which  the 
protoplasmic  filaments  were  prolonged  ran  for  the  most 
part  from  tip  to  tip  of  the  fusiform  cells  and  parallel  to 
their  long  axes. 

Outside  this  annular  zone,  (from  2  to  2.5  mm.  outside 
the  inner  epithelial  border,)  were  found  large  cells  in 
which  the  filaments  and  protoplasmic  bridges  were 
remarkably  well  developed  and  there  also  were  found 
mitoses.  It  is  therefore  in  this  area  that  new  cells  are 
formed.  In  this  zone  the  intercellular  spaces  are  larger 
than  elsewhere,  from  3  to  6  ^  wide,  whereas  1.8  to  3  M 
represents  the  mean  normal  figure  for  the  epidermis. 
This  considerable  enlargement  of  the  intercellular  spaces 
makes  it  possible  for  these  cells  to  store  up  the  larger 
quantity  of  nutritive  fluid  which  is  necessary  for  their 
more  intense  activity.12 

If  one  admits  for  the  moment  that  the  intercellular 
bridges  are  traversed  by  a  continuous  nervous  flux  this 
result  will  find  in  this  hypothesis  its  immediate 
explanation. 

In  order  to  make  our  idea  clearer  let  us  consider  the 
concrete  case  of  a  stream  of  flowing  water,  which  at  a 
certain  point  divides  up  into  several  branches.  Sooner 
or  later  a  dynamic  equilibrium  is  established  and  the 
quantity  of  water  flowing  during  each  unit  of  time  into 
each  of  the  branches  respectively  will  be  constant.  If 

"Siegfried  Garten:  Die  Interzellularbrucken  der  Epithelien  und 
ihre  Funktion.  Archiv  fiir  Anatomic  und  Physiologic.  Leipzig. 
1895-  P.  407—409. 


Action  of  Nervous  Currents  in  Skin  Wounds     35 

we  now  effect  artificially  the  obstruction  of  some  of 
these  branches  the  entire  volume  of  water  must  flow 
through  the  others  which  remain  open  and  their  volume 
of  water  will  consequently  be  increased  in  proportion. 

In  the  same  way  let  us  suppose  that  through  the 
intercellular  bridges  of  the  epidermis  for  example,  there 
go  similar  nervous  currents,  in  which  when  once  the 
organism  has  attained  its  adult  age  dynamic  equilibrium 
is  established.  And  let  us  remove  a  little  disc  of  skin 
as  Siegfried  Garten  did,  then  the  nervous  flux  which 
heretofore  had  taken  its  way  through  the  filaments  and 
protoplasmic  bridges  of  the  cells  situated  in  the  little  disc 
removed  will  now  find  these  ways  closed.  Consequently 
the  entire  flux  must  take  a  roundabout  way  through  the 
neighboring  parts  surrounding  the  little  disc. 

The  augmentation  of  the  nervous  current  in  these 
ways  will  have  as  its  result  an  augmentation  of  the  trophic 
stimulus  which  it  exercises;  so  that  the  cells  situated 
along  these  ways  will  grow  and  proliferate  more  rapidly, 
thus  producing  a  zone  of  reproduction  characterized  by 
numerous  mitoses.  The  augmentation  of  the  vital 
processes  of  these  cells  will  in  consequence  of  increased 
osmotic  attraction,  attract  a  greater  quantity  of  nutritive 
fluid,  exactly  as  the  wick  of  a  lamp  which  is  stimulated 
by  a  current  of  air  draws  up  by  capillarity  a  larger 
quantity  of  combustible  fluid.  And  this  greater  quantity 
of  nutritive  fluid  pressing  in  between  one  cell  and  another, 
will  distend  the  intercellular  spaces  so  that  in  this  zone 
they  undergo  an  enlargement.  The  further  the  new 
formation  of  the  skin  proceeds,  the  shorter  will  be  the 
way  through  which  the  abnormally  increased  nervous 
flux  tends  to  pass,  that  is  to  say  that  the  zone  of  the 


36  Nature  of  the  Formative  Stimulus 

most  intense  flux  and  the  zone  of  reproduction  thereby 
determined  will  approach  the  center  of  the  wound. 

The  tangential  disposition  of  the  cells  of  the  circular 
zone  between  the  reproductive  zone  and  the  central 
granular  zone,  would  be  due  just  to  this  nervous  flux 
which  commences  to  flow  through  the  new  formed  cells, 
but  is  still  always  forced  to  flow  around  the  wound  in 
some  such  way  as  the  water  of  a  river  flows  around 
the  circular  pier  of  a  bridge.  The  direction  of  the  cell 
axis  would  thus  be  determined  by  the  direction  of  the 
current. 

According  to  Siegfried  Garten's  views,  on  the  con- 
trary, there  would  exist  all  around  the  wound,  in  spite 
of  the  aseptic  dressing,  an  augmentation  of  the  blood 
circulation,  which  would  have  as  its  consequence  an 
increase  of  pressure  and  of  the  amount  of  nutritive 
fluid  in  the  tissue.  And  consequently  there  would  arise 
an  augmentation  of  volume  of  the  intercellular  spaces 
and  an  increased  formation  of  new  cells  in  the  reproduc- 
tive zone.  As  for  the  tangential  disposition  of  the  cells 
of  the  surrounding  zone,  he  believes  that  one  can  explain 
that  by  the  theory  of  sphincter  action,  that  is  through 
the  contraction  of  the  intercellular  bridges  of  these  cells. 
In  consequence  of  this  contraction  the  long  axis  of  the 
cells  would  turn  into  the  direction  of  the  tractile  force 
which  is  exercised  upon  the  cells.  At  the  same  time  the 
consequent  shortening  of  the  respective  circular  zones  of 
these  cells  wrould  cause  the  epithelium  to  press  in  toward 
the  center  of  the  granulating  surface,  and  thereby  effect 
the  gradual  contraction  of  the  opening  of  the  wound.13 

But  the  increased  blood  supply  and  the  shortening 

"Siegfried  Garten:    Ibid.  P.  409—411. 


Effects  of  Nervous  Currents  in  Skin  Wounds      37 

of  the  intercellular  bridges  which  this  explanation  pre- 
supposes would  require  to  be  explained  themselves.  It 
is  to  be  remembered  further  that  Roux  in  his  studies 
upon  the  struggle  of  the  parts  of  the  organism  has 
shown  that  the  great  affluence  of  necessary  nutritive  fluids 
is  always  the  consequence  rather  than  the  cause  of  the 
growth  of  the  organic  substance. 

This  experiment  of  Siegfried  Garten  argues  strongly 
in  favor  then  of  the  hypothesis  that  a  continuous  nervous 
flux  traverses  the  intercellular  bridges.  The  nuclei,  as 
foci  of  nervous  energy,  would  be  precisely  the  sources 
which  feed  it,  and  which  in  normal  conditions  preserve 
it  unaltered.  At  the  same  time,  the  nervous  flux  dis- 
charged by  the  other  nuclei  in  passing  through  any  one 
nucleus  acts  like  a  functional  trophic  stimulus,  in  so  far 
as  it  is  favorable  to  the  specific  vital  process  of  this 
nucleus.  Each  increase  or  decrease  of  this  current 
passing  through  certain  nuclei  caused  by  conditions  lying 
without  these  nuclei,  would  have  as  a  result  an  aug- 
mentation or  diminution  first  of  their  mass  and  later 
of  their  number. 

This  augmentation  of  the  nervous  flux  in  given  zones 
following  the  ablation  of  neighboring  parts  would  thus 
be  the  general  cause  of  the  active  proliferation  of  cells 
by  which  all  the  phenomena  of  reproduction  commence. 

Later  when  there  comes  into  play  a  disturbance  of 
the  equilibrium,  one  can  conceive  that  its  reestablish- 
ment  can  proceed  and  spread  from  any  one  whatever 
of  the  numerous  parts  which  surround  the  part  cut  off. 
In  other  and  more  general  terms  one  understands  that 
the  reestablishment  of  the  normal  distribution  of  nervous 
energy,  necessary  for  the  reformation  of  an  organ,  in 
case  it  be  prevented  from  following  the  ordinary  way, 


38  Nature  of  the  Formative  Stimulus 

can  reach  the  organ  by  any  other  way  and  indeed  by  a 
way  quite  the  opposite  of  the  normal  as  happens  for 
example  in  any  distribution  of  electric  or  hydrodynamic 
energy,  and  that  consequently  it  amounts  to  the  same 
thing  whether  the  regeneration  of  the  tissue  or  of  the 
organ  ablated  proceeds  in  the  same  way  as  in  ontogeny 
or  by  any  other  way. 

And  finally  we  must  suppose  that  regeneration  is 
nothing  else  than  a  particular  case  of  generation  or 
reproduction  and  that  the  nature  of  one  is  substantially 
identical  with  that  of  the  other:  for,  to  use  the  words 
of  Delage  "generation  is  only  the  regeneration  of  a 
complete  organism  by  a  portion  of  greater  or  less  size 
attached  to  it  or  detached  from  it;"  14  so  the  causes  of 
the  regeneration,  for  instance  of  a  little  disc  of  skin 
which  has  been  removed,  must  be  essentially  the  same 
as  those  which  effect  a  complete  reproduction. 

Between  the  two  phenomena  the  following  difference 
will  however  exist:  The  regeneration  of  a  little  disc 
of  skin  will  be  due,  according  to  what  we  have  just  stated, 
to  the  fact  that  the  continuous  nervous  flux  which  flows 
through  the  whole  organism  and  particularly  through 
those  parts  which  were  contiguous  with  the  part  removed, 
would  tend  to  reestablish  its  dynamic  equilibrium,  dis- 
turbed by  the  operation.  If  we  accept  the  fundamental 
biogenetic  law  in  its  first  degree  of  approximation, 
complete  generation,  on  the  contrary,  would  be  a  whole 
series  of  transitions  of  the  nervous  energy  circulating  or 
distributed  in  the  developing  organism,  from  one  dynamic 
system  to  the  other  next  in  order,  both  meanwhile  being 
in  a  state  of  equilibrium  since  they  were  already  formerly 

14Delage :  L'heredite  et  les  grands  problemes  de  la  biologic 
generate.  P.  98. 


Protoplasmic  Connections  of  Adjoining  Cells      39 

in  equilibrium  in  both  the  corresponding  phylogenetic 
forms.  To  effect  the  transition  it  is  necessary  then  that 
in  each  ontogenetic  stage  there  suddenly  supervene  at 
some  point  of  the  system  a  change,  which  disturbs  the 
established  equilibrium  and  provokes  the  passage  of  the 
continuous  nervous  flux  to  a  new  dynamic  equilibrium. 

If  the  intercellular  bridges  have  really  the  significance 
which  we  have  attributed  to  them,  one  can  see  how  they 
must  be  present  in  all  organisms  and  in  all  stages  of 
development.  It  is  superfluous  to  go  more  thoroughly 
here  into  the  fact  that  this  is  exactly  what  is  fully 
confirmed  by  histologic  investigations  which  are  being 
ever  more  carefully  prosecuted. 

We  recall  for  example  the  protoplasmic  connection 
observed  by  Hammar  between  the  segmentation  spheres 
of  the  sea  urchin  egg:  The  cells  of  the  blastula  are 
covered  all  over  the  outside  of  it  by  a  protoplasmic  layer 
which  adheres  in  each  cell  only  to  the  part  of  its  surface 
which  is  directed  toward  the  outside.  This  layer  in  a 
few  preparations  not  sufficiently  protected  against  drying 
separated  itself  a  little  from  the  blastula.  There  appeared 
then  thin  filaments,  variable  in  number  and  more  or  less 
regular  in  disposition,  which  extended  from  the  granular 
protoplasm  of  the  different  blastomeres  to  the  interior  of 
this  layer  and  produced  in  this  way  a  manifold  connection 
of  the  different  cells  with  one  another.15 

Sedgewick  has  observed  the  same  thing  in  the  develop- 
ment of  the  eggs  of  Peripatus.  The  two  cells  which 
come  from  the  cleavage  of  the  eggs  are  not  completely 

lcHammar:  Ubereinen  primaren  Zusammenhang  zwischen  den 
Furchungszellen  des  Seeigeleies.  Archiv  fur  mikrosk.  Anat.  und 
Entwicklungsgesch.  Bd.  XLVII.  Erstes  Heft.  Bonn,  Cohen.  1896. 
P.  I4ff. 


40  Nature  of  the  Formative  Stimulus 

separated  but  remain  connected  by  protoplasmic  fila- 
ments; the  cells  which  arise  from  each  of  the  first  two 
cells  are  associated  in  the  same  manner,  and  this  con- 
tinues indefinitely.  So  that  during  the  whole  of  develop- 
ment from  the  first  segmentation  of  the  egg  up  to  the 
adult  stage  all  the  cells  of  the  organism  remain  in  inter- 
communication by  means  of  these  protoplasmic  bridges. 
"The  connection  of  cell  with  cell  is  not  a  secondary 
feature  acquired  late  in  development,  but  is  primary 
dating  from  the  very  beginning  of  development."  16 

It  is  quite  unnecessary  to  recall  the  universality  of 
intercellular  bridges  not  only  between  the  cells  of  each 
tissue  but  also  between  the  cells  of  different  tissues: 
between  the  epithelial  cells  of  gland  ducts  and  contiguous 
smooth  muscle  cells,  between  epithelial  cells  and  con- 
nective tissue  cells,  between  connective  tissue  cells  and 
endothelial  cells,  between  smooth  muscle  cells  and  con- 
nective tissue  cells,  between  connective  tissue  cells  and 
striated  muscle  fibers,  between  striated  muscle  fibers  and 
epithelial  cells,  and  so  on.17 

It  is  necessary  to  be  remarked  further  that  in  animals 
this  circulation  of  nervous  currents  can  and  at  least  in 
certain  stages  of  development  must  certainly  utilize 
not  only  the  protoplasmic  network  uniting  the  cells  to 


16Adam  Sedgwick:  The  Development  of  the  Cape  Species  of 
Peripatus.  Quart.  Journ.  of  microscopical  Science.  XXVI,  1886.  P. 
198—200,  206. 

"See  for  instance:  Heidenhain:  Uber  das  Vorkommen  von 
Interzellularbriicken  zwischen  glatten  Muskelzellen  und  Epithelzellen 
des  ausseren  Keimblattes  und  deren  theoretische  Bedeutung.  Anat. 
Anzeiger,  VIII,  No.  12  and  13;  May  13,  1893;  P.  404 — 410;  and 
Schuberg:  Uber  den  Zusammenhang  verschiedener  Gewebezellen  ina 
tierischen  Organismus.  From  the  Sitzungsberichten  der  Phys.-Med. 
Gesellschaft  zu  Wurzburg.  Sitzung  vorn  Febr.  25,  1893;  P.  I— 8. 


The  Whole  Organism  a  Great  Protoplasmic  Plexus  41 

one  another,  but  also  the  nervous  system  itself  with  all 
its  fibers  and  fibrils  in  so  far  as  it  is  developed.  This 
leads  to  the  conclusion  that  in  the  adult  organism  the 
ordinary  nervous  currents  passing  along  the  various 
nerves  as  a  result  of  ordinary  nervous  discharges  con- 
stitute only  momentary  intensifications  of  permanent 
nervous  currents  which  pass  continually  through  these 
nerves. 

The  great  frequency  with  which  conductors  of  nuclear 
stimuli  in  general  and  intercellular  bridges  in  particular, 
are  found  in  both  animal  and  vegetable  kingdoms,  is 
as  we  have  said,  even  by  itself  a  very  strong  support  for 
the  hypothesis  proposed  by  us  of  a  nervous  circulation 
or  distribution  throughout  the  whole  organism. 

In  this  hypothesis  we  approach,  even  though  only  in 
certain  respects,  the  most  recent  theories  of  some  botan- 
ists and  physiologists  who  in  consideration  of  this 
striking  general  protoplasmic  connection  between  the 
different  cells,  regard  the  multicellular  organism  not  as  a 
mere  assembly  or  colony  of  cells,  but  rather  as  a  single 
voluminous  protoplasmic  body  in  which  the  nuclei  are 
inserted  at  different  intervals  as  centers  or  foci  of 
energy,  (synergids  of  Sachs),  and  in  which  the  mem- 
branes and  other  intermediate  structures  have  produced 
only  incomplete  divisions  and  serve  merely  as  supports 
of  the  organism.  For  example,  according  to  Sedgewick 
the  body  of  the  adult  animal  would  be  only  an  immense 
syncytium  whose  nuclei  or  centers  of  force  are  dispersed 
throughout  a  single  protoplasmic  network  binding 
together  the  whole  organism.18 

We  approach  especially  the  conception  which  Oscar 

"Adam  Sedgwick:  The  Development  of  the  Cape  Species  of 
Peripatus.  P.  205—206. 


42  Nature  of  the  Formative  Stimulus 

Hertwig  seems  to  have  of  protoplasmic  connections,  for 
while  it  is  true  that  he  never  discusses  such  a  continuous 
nervous  flux  and  speaks  only  of  the  transmission  of 
nuclear  stimuli,  nevertheless  this  latter  conception  in  our 
mind  implies  the  former.  To  sum  up  our  conception  of 
these  protoplasmic  connections  we  could  almost  adopt 
the  very  words  of  this  investigator :  "It  is  probable  that 
this  transmission  of  nuclear  stimuli  by  protoplasmic  fila- 
ments will  be  much  less  rapid  and  less  intensive  than 
nerve  conduction,  but  perhaps  for  this  very  reason  will 
be  more  continuous  and  by  reason  of  its  duration  more 
efficacious."  19 

It  is  quite  unnecessary  to  draw  especial  attention  to 
the  fact  that  the  vegetable  kingdom  is  not  in  any  way  an 
obstacle  to  this  conception  of  a  continuous  nervous  flux 
throughout  the  whole  organism,  for  if  nervous  phe- 
nomena are  less  apparent  in  it  than  in  the  animal  kingdom, 
they  constitute  nevertheless  just  as  in  the  latter  the  essence 
of  the  vital  phenomenon. 

From  amoeboid  movements,  from  the  vibrations  of 
cilia  and  flagella  up  to  the  most  complex  psychic  phe- 
nomena, everywhere  where  life  is,  one  finds  also  processes 
of  nervous  nature.  The  reticular  or  fibrillar  structure 
which  protoplasm  in  general  exhibits,  protoplasmic 
currents,  especially  those  in  very  long,  fine  filaments, 
such  as  for  example  those  in  the  pseudopodia  of  the 
rhizipod  Gromia  oviformis,  which  by  their  peculiar 
character  make  one  suspect  that  they  may  be  only  the 
consequence  and  sensible  effect  of  currents  provoked  by 
an  energy  of  another  kind,  the  striations  consisting  of 
bundles  of  curved  parallel  lines  without  sharp  angles  in 

"Oscar  Hertwig:   Die  Zelle  und  die  Gewebe.    Zw.  Buch.  P.  40, 


Protoplasmic  Nervous  Currents  Universal        43 

each  little  layer  of  the  cell  membranes  of  plants,  the 
formation  of  a  membrane  in  an  anuclear  fragment  of  a 
vegetable  cell  in  consequence  of  a  nuclear  stimulus  trans- 
mitted from  the  nucleus  of  another  cell  along  any  proto- 
plasmic conductor,  all  these  facts  speak  together  in  favor 
of  the  hypothesis  that  all  living  substance  is  traversed 
by  vital  nervous  energy  in  the  form  of  currents. 

Claude  Bernard  has  already  remarked  that  anaesthe- 
tics act  not  only  upon  the  nervous  system  but  also  upon 
the  cells  of  every  animal  or  vegetable  tissue,  in  that 
they  destroy  or  suspend  the  vital  activity  of  every  cell 
in  the  same  way,  and  from  that  he  concludes  that  all 
vital  processes  in  general  are  substantially  identical.20 

This  substantial  identity  is  demonstrated  further  by 
the  fact  that  phenomena  of  irrito-contractility  present 
themselves  in  the  same  way  in  both  animal  and  vegetable 
kingdoms  and  that  there  are  all  possible  transition 
stages  between  plants  considered  "especially  sensitive" 
and  those  considered  not  sensitive  at  all.  The  whole 
group  of  "especially  sensitive"  plants  present  especially 
well  developed  intercellular  protoplasmic  connections.21 

We  recall  further  the  microscopic  movements  of  the 
protoplasm  within  the  membranes  of  plant  cells,  which 
led  Huxley  to  make  the  well  known  definition  that  a 
plant  is  only  "an  animal  shut  up  in  a  wooden  box." 

Everybody  knows  that  in  addition  to  these  micro- 
scopic movements  there  are  now  known  in  plants  also 
various  movements  visible  to  the  naked  eye,  which  cor- 


20Claude  Bernard :  Legons  sur  les  phenomenes  de  la  vie  communs 
aux  animaux  et  aux  vegetaux.  Paris,  Bailliere,  1878.  P.  289—290. 

21Macfarlane:  Irrito-contractility  in  plants.  Biol.  Lect.  at  the 
Mar.  Biol.  Lab.  of  Wood's  Roll.  Summer  Session  1893.  Boston, 
U.  S.  A.,  Ginn.  1894.  P.  189,  204. 


44  Nature  of  the  Formative  Stimulus 

respond  fully  with  the  reflex  movements  of  animals ;  that 
is,  in  which  one  can  distinguish  as  in  animals  a  region  of 
perception  and  another  of  motility,  as  well  as  the 
transmission  of  a  stimulus  from  the  perceptive  region  to 
the  motor  region. 

Leaving  aside  the  very  well  known  example  of 
Mimosa  it  suffices  to  recall  for  example,  that  in  certain 
plants  one  can  demonstrate  that  the  sensibility  of  the 
root  to  gravitation  resides  in  its  extreme  tip  while 
the  bending  movements  of  that  same  root  in  order  to 
resume  its  vertical  position  after  it  has  been  disturbed 
takes  place  in  another  part.  In  the  same  way  the  vertical 
position  of  the  stem  is  maintained.  But  a  yet  more 
typical  example  is  furnished  by  the  grass,  Setaria.  "It 
has  a  remarkable  manner  of  germination ;  as  soon  as  the 
seed  germinates  it  does  not  produce  a  simple  cylindrical 
stem  but  one  terminating  in  a  wedge  shaped  tip  like  a 
lance  head.  When  a  group  of  Setaria  is  lighted  from 
one  side  it  inclines  strongly  toward  that  side  and  all  the 
lance  tips  point  toward  the  light.  But  these  tips  are  not 
curved  at  all,  on  the  contrary  the  whole  bending  is 
produced  in  the  stem,  although  it  is  clearly  these  tips 
which  are  sensitive  to  light  and  not  the  stems.  It  is  easy 
.to  prove  this  by  covering  the  tops  of  some  stems  with 
an  opaque  cap:  the  grass  stalks  so  protected  remain 
vertical  while  others  incline  their  stems  toward  the  light. 
The  part  that  bends  has  not  then  any  sensitiveness  to 
light  and  the  part  sensitive  to  light  does  not  bend.  The 
little  lance  is  the  organ  of  perception,  the  stem  the 
motile  region,  and  it  is  clear  that  a  stimulus  is  transmitted 
from  the  tip  to  the  stem."  22 

22Francis   Darwin:    Le   mouvement   chez   les   plantes.     Revue 
scientifique.     March  i,  1902.     P.  265. 


Specific  Modes  of  Being  of  Nervous  Currents    45 

Consequently  the  view  is  not  only  justified  but  almost 
required  that  in  plant  bodies  also  there  is  a  nervous  cir- 
culation or  distribution,  which,  though  it  manifests  itself 
only  in  its  variations  dependent  on  some  change  in  the 
external  influences,  is  certainly  none  the  less  present 
during  the  repose  of  the  organism  when  it  is  in  a  state 
of  dynamic  equilibrium.  It  is  this  constant  circulation 
or  continuous  distribution  of  nervous  energy,  which  con- 
stitutes in  plants  quite  as  well  as  in  animals  the  "small 
yet  mighty  link"  which  unites  the  parts  of  the  organism 
into  a  "sympathetic  whole,"  a  function  which  Lewes 
ascribes  especially  to  the  nervous  system.23 

As  to  the  properties  of  each  of  the  respective  excita- 
tations  or  currents  which  constitute  this  general  nervous 
flux,  it  is  sufficient  for  our  purpose  to  suppose  that  these 
latter  appear  in  specifically  differing  modes  of  existence 
which  are  capable  now  of  combining  now  of  disjoining; 
we  mean  by  this  that  two  specific  modes  of  being  are 
able  for  example  to  combine  with  each  other  and  so  to 
give  rise  to  a  third  specific  mode  of  being,  or  indeed  that 
this  latter  can  break  up  giving  rise  to  the  two  preceding 
specific  modes  of  being  or  even  to  others  different  from 
them. 

While  for  the  present  we  are  not  in  a  position  to 
discover  what  these  different  specific  modes  of  being 
really  are,  yet  we  can  and  indeed  must  necessarily  regard 
them  as  existing  since  in  different  tissues  different  specific 
nuclear  stimuli  must  certainly  be  present  in  the  cells. 
These  different  specific  modes  of  being  might  consist  in 
something  analogous  with  the  intensity  of  the  continuous 
electric  current,  or  perhaps  in  a  rhythmic  form  correspond- 

"Lewes:  The  physical  basis  of  mind.  New  edition.  London. 
Kegan  Paul,  Trench,  Triibner  &  Co.  1893.  P.  61. 


46  Nature  of  the  Formative  Stimulus 

ing  somewhat  for  example  with  the  alternating  electric 
current,  or  indeed  might  arise  in  another  way  of  which 
perhaps  we  can  not  in  advance  form  any  conception  at  all. 
It  is  sufficient  for  our  purpose,  we  repeat,  to  suppose  that 
these  specific  modes  of  being  can  combine  and  break  up 
according  to  laws  which  are  definite  even  though  so  far 
quite  unknown.  For  the  very  fact  of  the  existence  of 
these  laws  would  imply  also  the  existence  of  correspond- 
ing laws  on  which  the  circulation  or  distribution  of 
nervous  energy  in  definite  networks  would  depend. 

If  one  accepts  such  a  hypothesis  of  the  circulation 
or  the  distribution  of  nervous  energy  in  the  organism, 
one  could  find  the  immediate  explanation  of  certain 
phenomena  of  development  whose  cause  has  so  far 
remained  a  secret.  These  phenomena  consist  in  the  recip- 
rocal influences  which  certain  parts  of  the  embryo,  even 
though  widely  separated,  exert  upon  one  another  in  spite 
of  the  lack  of  any  functional  adaptation  and  by  which  the 
development  of  these  parts  is  wholly  or  partially 
determined. 

One  can,  indeed,  attempt  to  give  the  beginning  of 
an  explanation  of  these  phenomena  of  correlation,  by 
supposing  the  different  parts  which  exercise  this  reciprocal 
influence  to  be  situated,  maybe  upon  the  same  partial 
network  of  the  general  circulatory  system,  maybe  upon 
different  partial  networks  which  nevertheless  come  off 
at  one  common  given  point  from  the  same  principal 
branch,  or  maybe  finally,  in  the  case  of  contiguous  parts, 
upon  different  partial  networks  which  are  however 
provided  with  direct  communications  between  some  of 
their  respective  nuclei.  The  absence  of  any  analogous 
reciprocal  action  between  other  parts  also  contiguous 
may  be  explained  by  the  lack  of  any  such  direct  con- 


Correlative  Differentiation  and  Growth          47 

nection  between  the  nuclei  of  the  two  partial  networks 
belonging  to  these  parts,  a  fact  which  renders  these  net- 
works in  certain  respects  quite  independent  of  one  another 
if  at  the  same  time  they  do  not  come  from  a  common 
principal  branch. 

It  would  be  "a  very  important  matter,"  writes  Delage 
"to  know  if  secondary  protoplasmic  connections  are 
formed  between  neighboring  cells  which  are  not  sisters 
but  which  have  been  brought  only  secondarily  into  contact 
with  one  another,  for  example  after  an  mvagination  in 
animals  or  through  grafting  in  plants."  24  In  the  cases 
in  which  this  did  not  occur  one  could  then  have  the 
simultaneous  and  to  a  certain  extent  independent  exist- 
ence of  partial  circulatory  systems  even  though  they  lie 
close  together  or  perhaps  even  enclose  each  other. 

Roux  designates  by  the  term  "correlative  or  dependent 
differentiation"  the  complete  or  partial  determination  of 
development  by  reciprocal  influences  of  epigenetic  nature 
which  become  established,  in  a  certain  measure  at  least 
as  he  admits  himself,  between,  the  cells.  We  can  then 
designate  these  partial  networks  of  the  general  cir- 
culatory system  by  the  name  "networks  of  correlation." 
And  we  shall  see  that,  conformably  with  our  theoretical 
conjectures  very  many  processes  seem  actually  to  prove 
that  each  of  these  networks  is  capable  of  existence  by 
itself,  independent  within  certain  limits  of  other  partial 
networks. 

Among  the  phenomena  of  correlative  differentiation 
in  development  belong  also  those  which  are  called  com- 
pensatory growths.  The  investigations  of  Ribbert  ( 1889) 
and  his  pupils  upon  the  mammals  have  shown  especially 

"Delage:  L'heredite  et  les  grands  problemes  de  la  biologic  gen- 
erale.  P.  33. 


48  Nature  of  the  Formative  Stimulus 

well,  that  after  the  cutting  off  of  organs  not  yet  in 
function,  for  example  of  the  testicle  or  of  an  infantile 
ovary  or  several  infantile  milk  glands,  the  other  similar 
organs  underwent  in  their  respective  parts  a  proportionate 
growth  as  though  they  would  thus  compensate  for  absent 
parts.  It  would  appear  from  this  that  the  networks  of 
correlation  belonging  to  each  of  these  parts  of  like  organs 
must  come  off  from  a  common  principal  branch  in  such 
a  way  that  the  whole  current  of  this  branch  prevented 
from  the  usual  division  by  the  absence  of  one  part  of 
the  network  would  now  discharge  itself  entirely  into 
the  remaining  organ. 

The  hypothesis  of  the  continuous  circulation  or  the 
continuous  general  distribution  of  nervous  energy  which 
thus  finds  its  support  in  certain  special  phenomena  of 
development,  affords  better  than  any  other  an  explana- 
tion for  the  fundamental  process  of  every  ontogeny, 
which  consists  as  Roux  has  very  aptly  said  only  in  a 
series  of  unequal  localizations  of  growth. 

"A  given  region  grows,"  wrrites  Delage,  "while  the 
neighboring  parts  by  which  it  is  surrounded,  grow  much 
less  or  not  at  all.  This  part  must  necessarily  then  project 
outward  or  become  invaginated  and  form  a  cavity.  But 
at  a  given  moment  growth  ceases  in  this  place  and  goes 
over  to  another  place,  and  the  same  phenomenon  is  now 
repeated  at  this  new  place/' 25 

The  morphological  means  which  ontogeny  employs  is 
then  always  the  same,  always  of  the  same  identical  nature 
even  when  the  tissues  already  partially  differentiated 
commence  to  differ  from  one  another  in  their  most 
essential  properties. 

2BDelage:  L'heredite  et  les  grands  problemes  de  la  biologie 
generate.  P.  174. 


Explanation  of  Onto  gene  tic  Involutions          49 

The  hypothesis  of  a  continuous  trophic  nervous  flux 
being  admitted,  these  serial  unequal  localizations  of 
growth  can  be  explained  by  changes  in  the  distribution  of 
this  flux  at  each  new  ontogenetic  stage,  from  causes 
which  we  shall  examine  in  the  next  chapter.  These 
changes  of  distribution  bring  about  now  here,  now  there, 
a  great  affluence  of  nervous  energy  and  thereby  induce 
at  the  corresponding  points  proliferation  of  the  cells  from 
which  must  necessarily  arise  later  the  invagination  or 
evagination  in  question. 

But  the  ontogenetic  phenomena  which  most  clearly 
call  for  the  conception  of  such  a  distribution  of  nervous 
energy  which  continually  changes  and  shifts,  streaming 
now  through  one  region  now  another  of  the  developing 
organism,  are  the  phenomena  of  involution;  that  is  to 
say  phenomena  of  reduction  presented  by  the  tissues  of 
an  organ  which  after  being  formed  in  the  course  of 
ontogeny  tends  at  a  later  stage  to  disappear;  for  example 
the  involution  of  the  tail  of  a  tadpole  during  its  meta- 
morphosis into  a  frog. 

The  atrophy  and  degeneration  of  the  skin,  of  the 
notocord,  of  nerve  and  muscle  fibers,  by  which  this 
involution  is  produced,  have  been  described  particularly 
by  Osborn.  He  as  well  as  Metschnikoff  has  established 
in  this  connection  the  great  phagocytic  activity  of  certain 
cells  and  the  formation  of  true  and  false  giant  cells. 
Nevertheless  he  does  not  attribute  to  the  phagocytes  the 
most  important  role  in  the  elimination  of  material.  The 
whole  of  the  process,  in  fact,  results  in  the  gathering 
together  of  the  cellular  material  in  process  of  dis- 
integration and  conducting  it  into  the  lymph  and  blood 
vessels  for  utilization  later  in  the  construction  of  other 
organs  and  tissues  peculiar  to  the  adult  animal. 


50  Nature  of  the  Formative  Stimulus 

This  would  indicate  then  that  the  greater  phagocytic 
activity  would  be  not  so  much  the  cause  as  rather  the 
effect  of  the  diminution  of  the  vital  resistance  of  the 
organ.  And  this  latter  would  seem  necessarily  to  be 
due  exclusively  to  the  fact  that  the  organ  itself  would 
be  at  this  ontogenetic  stage  abandoned  by  the  particular 
energy  which  had  formed  it,  and  which  up  till  now 
had  maintained  it  in  full  vital  activity,  and  which  now 
has  not  indeed  ceased  to  exist,  but  has  turned  to  other 
regions.  This  transference  of  cellular  material  in  process 
of  disintegration  to  other  organs  and  tissues  in  process 
of  formation  would  seem  in  fact  to  demonstrate  that 
simultaneously  with  the  diminution  or  the  cessation  of 
the  trophic  stimulus  in  one  given  region  there  appears 
an  increase  of  that  stimulus  in  another  region. 

This  utilization,  as  nutritive  material,  of  the  substance 
of  cells  which  are  disintegrating  is  rendered  necessary  by 
the  fact  that  animals  during  their  metamorphosis  take 
almost  no  nourishment.  It  follows  that,  if  the  nutritive 
material  which  the  abandoned  parts  give  up  to  the  parts 
now  more  abundantly  infused  with  trophic  energy,  should 
be  insufficient  at  the  normal  rapidity  of  disintegration, 
the  disappearance  of  the  tissues  must  be  accelerated.  This 
is  indicated  by  Osborn's  researches  upon  the  influence  of 
fasting  upon  metamorphosis,  from  which  it  appears  that 
it  is  appreciably  accelerated  by  inanition,  just  because  of 
the  more  rapid  reduction  and  absorption  of  the  organs 
about  to  disappear.26 

In  the  disappearance  of  the  tail  of  the  tadpole  one  has 
not  a  senile  but  rather  a  premature  involution  of  tissues, 

26Osborn:  Alte  und  neue  Probleme  der  Phylogenese.  Ergebn. 
d.  Anat.  u.  Entwicklungsgesch.,  herausg.  v.  Merkel  u.  Bonnet.  Bd. 
III.  1893.  Wiesbaden,  Bergmann.  1894.  P.  I9& 


Distribution  of  Energy  Explains  Ontogeny        51 

"in  which  nature  destroys  in  a  manner  which  may  seem 
to  us  cruel,  cells  which  have  just  been  produced."  The 
hypothesis  of  the  distribution  of  trophic  nervous  energy 
seems  to  us  the  only  one  which  can  give  a  satisfactory  ex- 
planation of  this  phenomenon. 

The  struggle  of  the  parts  of  the  organism  cannot  in 
fact  be  the  exclusive  cause  of  this  involution  of  young 
tissues.  This  struggle  is  not  sufficient  by  itself  to  explain 
the  exactness  of  the  epoch  and  of  the  stage  of  develop- 
ment at  which  this  physiological  involution  takes  place. 
Even  if  we  were  willing  to  admit  that  this  struggle  has 
some  effective  participation  in  the  production  of  this 
phenomenon,  we  must  nevertheless  admit  that  in  addition 
an  inciting  ontogenetic  stimulus,  as  Roux  would  say, 
must  at  the  appointed  time  exert  its  trophic  action  upon 
the  parts  destined  to  victory,  while  it  abandons  others 
previously  favored,  but  which  now  are  devoted  to  destruc- 
tion. The  distribution  of  trophic  nervous  energy  with  its 
changes  would  thus  always  remain  the  only  cause  of  the 
phenomenon. 

But  if  ontogenetic  physiological  involutions  are  due  to 
the  fact  that  the  distribution  of  trophic  nervous  energy 
abandons  one  region  to  turn  to  another,  similar  changes 
and  shifting  of  this  distribution  must  then  be  likewise 
the  cause  of  all  invaginations  and  evaginations,  of  all 
morphological  phenomena  in  general  and,  with  much 
probability,  consequently,  of  those  ontogenetic  phenomena 
also  which  are  not  exclusively  morphological  in  nature. 

To  produce  each  one  of  these  serial  ontogenetic  mod- 
ifications in  the  distribution  of  trophic  nervous  energy  it 
would  suffice  theoretically  that  at  the  required  moment 
there  become  active,  were  it  only  upon  one  certain  point 
of  the  circulatory  system,  a  single  new  definite  specific 


52  Nature  of  the  Formative  Stimulus 

current,  different  from  the  current  previously  present  at 
the  same  point.  And  this  would  be  exactly  the  role,  which 
as  we  have  already  said  the  central  zone  of  development 
plays.  This  zone  therefore  will  be  the  object  of  our  study 
in  the  next  chapter. 


CHAPTER  THREE 

PHENOMENA    WHICH     POINT    TO     THE    EXISTENCE    OF    A 

CENTRAL    ZONE     OF    DEVELOPMENT HYPOTHESIS     OF 

THE  STRUCTURE  OF  THE  GERMINAL  SUBSTANCE. 

i.     Phenomena    Which    Point    to    the   Existence    of   a 
Central  Zone  of  Development 

The  only  group  of  organisms  in  which  one  can  say 
that  the  existence  of  a  central  zone  of  development  is  di- 
rectly demonstrated  is  that  of  the  unicellular  organisms, 
in  which  this  zone  is  constituted  by  the  nucleus.  In 
pluricellular  organisms  it  is  only  indirectly  that  we  are 
able  to  arrive  at  the  conclusion  that  the  central  zone 
exists. 

Experiment  has  shown  that  the  necessary  and  suffi- 
cient condition  for  the  ontogenetic  development  of  the 
Infusoria  is  the  presence  of  a  nucleus.  This  latter  con- 
stitutes therefore  for  them  an  effective  central  zone  of 
development  and  consequently  ontogenesis  consists  in 
them  in  a  true  and  proper  centroepigenesis. 

If  one  divides  an  amoeba  or  a  rhizopod  or  an  infuso- 
rian  already  completely  developed,  into  many  pieces,  that 
one  of  these  fragments  which  remains  provided  with  its 
nucleus  though  it  be  the  smallest  of  all,  is  yet  capable  of 
reproducing  by  new  formation  all  the  missing  organs  and 
of  developing  again  into  a  normal  individual ;  whereas  the 


53 


54    Indications  of  a  Central  Zone  of  Development 

other  fragments,  without  nuclei,  are  incapable  of  it  even 
though  they  may  be  much  larger. 

Especially  we  recall  the  researches  upon  artificial  di- 
vision of  the  Infusoria  made  by  Nussbaum  and  Gruber. 
If,  for  example,  one  cuts  a  stentor  into  three  pieces,  of 
which  each  contains  one  portion  of  its  moniliform  nucleus, 
in  the  space  of  twenty-four  hours  each  piece  regenerates 
the  missing  part.  The  anterior  extremity  regenerates  the 
posterior  and  vice  versa ;  the  middle  piece  reforms  the  two 
extremities,  that  is  to  say,  both  the  rather  complex  peri- 
stomal  region  with  its  mouth,  its  pharynx,  its  long  cilia, 
etc.,  and  also  the  simpler  posterior  part.  If  however  the 
fragment  retains  no  part  either  of  the  paranucleus  or  of 
the  nucleus  proper,  even  though  it  may  be  of  much 
greater  size  than  those  fragments  retaining  the  nuclei,  no 
trace  of  regeneration  is  observed,  a  fact  which  does  not 
prevent  the  piece  concerned  from  continuing  to  live  for  a 
while,  even  for  two  or  three  days,  nor  from  retaining  com- 
pletely the  capacity  of  locomotion,  of  vibration  of  cilia, 
of  pulsation  of  the  contractile  vesicle,  of  defecation,  of 
capturing,  engulfing  and  digesting  its  food.27 

Gruber  reports  however  the  following  experiment 
which  has  caused  a  good  deal  of  surprise,  for  according 
to  the  view  of  some  biologists  it  seems  to  be  opposed  to 
the  results  of  earlier  researches. 

He  selected  a  Stentor  coerelus  which  showed  already 
the  first  stages  of  spontaneous  division,  that  is  there  had 
already  commenced  in  it  the  formation  of  a  lateral,  per- 

27See  e.  g.  Balbiani :  Recherches  experimentales  sur  la  merotomie 
des  infusoires  cilies.  Recueil  Zool.  Suisse,  t.  V,  no.  I,  1888.  P.  48 — 
49,  54;  und  Verworn :  Die  physiologische  Bedeutung  des  Zellkerns. 
Archiv  fur  die  gesamte  Physiologic,  Band.  41.  Bonn,  Strau/3,  1892. 
P.  13—14- 


Objection  of  Anuclear  Regeneration  in  S  tent  or    55 

istomal,  ciliated  area,  and  he  divided  it  in  two  halves. 
Since  in  this  stage  the  chief  nucleus,  ordinarily  monili- 
form,  contracts  into  a  round  or  bean  shaped  mass, 
Gruber  was  able  to  remove  it  completely  from  both 
halves.  The  division  of  the  animal  was  effected  in  such 
a  way  as  to  produce  about  the  same  two  halves  as  would 
later  have  been  produced  by  spontaneous  division.  In  the 
fragment  which  contained  the  original  peristome  the 
simple  cicatrization  of  the  wound  was  enough  to  repro- 
duce a  complete  individual.  In  the  other  fragment  which 
contained  the  posterior  extremity  the  wound  closed  in 
the  same  way  and  the  anterior  extremity  continued  its 
development  until  the  peristomal  area  and  the  buccal 
spiral  were  completely  formed.28 

This  result  seemed  to  contradict  the  view  that  the 
formative  action  of  a  nucleus,  as  .a  developmental  center 
for  the  unicellular  organism,  was  exerted  continuously 
throughout  the  whole  duration  of  development.  But  the 
following  considerations  show  that  this  premature  con- 
clusion is  quite  fallacious. 

We  should  remember  in  this  connection  another  ob- 
servation of  Gruber.  He  cut  off  from  the  anterior  end 
of  a  Stentor  a  fragment  absolutely  without  a  nucleus,  but 
containing  a  small  portion  of  the  peristomal  band.  The 
cicatrization  of  the  wound  was  followed  by  the  ordinary 
contraction  of  the  fragment  and  thereby  the  small  portion 
of  the  peristomal  band  was  given  the  appearance  of  a 
complete  Infusorian  such  as  would  be  formed  by  regen- 

28Gruber:  Uber  kiinstliche  Teilung  der  Infusorien.  Zweite 
Mitteilung.  Biol.  Centralbl.  Band,  V,  No.  5;  May  i,  1885.  P.  139— 
140;  und :  Beitrage  zur  Kenntnis  der  Physiologic  und  Biologic  der 
Protozoen;  Berichte  der  Naturforschenden  Gesellsch.  zu  Freiburg 
j.  B.,  Freiburg  i.  B.,  Mohr,  1886,  P.  13—14. 


56    Indications  of  a  Central  Zone  of  Development 

eration.  But  that  this  was  not  actually  the  case  was 
demonstrated  by  more  careful  observation  by  which  it 
was  recognized  that  the  completeness  was  only  apparent, 
for  no  part  altogether  lost  was  reproduced  and  no  new 
mouth  was  formed  in  the  place  of  the  old  one  which  had 
been  removed.29 

From  this  one  could  almost  infer  that  some  analogous 
phenomenon  is  the  effective  cause  whereby  the  organs  of 
the  peristomal  field,  as  soon  as  they  are  all  formed  in  their 
essential  parts,  become  arranged  in  the  posterior  anuclear 
half  in  about  the  same  way  as  they  would  be  arranged 
after  the  completion  of  spontaneous  division. 

Even  if  we  admit  a  true  and  proper  continuation  of 
development,  we  must  yet  bear  in  mind  first  that  it  is  not 
at  all  certain  that  this  posterior  half  was  completely  de- 
prived of  macro-  or  micro-nuclear  substance.  For  the 
micro-nuclei  sometimes  attain  the  number  of  fifty- four  or 
sixty-six  in  Stentor  coereleus,  and  it  is  always  difficult  to 
see  them,  especially  in  individuals  in  process  of  sponta- 
neous division.30 

Secondly  we  must  above  all  things  get  a  clear  under- 
standing of  what  the  remaining  alive  for  a  while  of 
anuclear  fragments  of  adult  individuals  can  signify,  keep- 
ing in  view  at  the  same  time  the  absolute  generative  inca- 
pacity of  these  fragments.  They  signify  nothing  else  than 
a  posthumous  persistence  for  a  while  of  the  special  action 
or  series  of  actions,  partly  simultaneous,  partly  succes- 


29Gruber:  Uber  Kiinstliche  Teilung  der  Infusorien.  Zweite 
Mitteilung.  Biol.  Centralbl.,  Bd.,  V.  No.  5;  May  I.  P.  139—140. 

80H.  P.  Johnson :  A  Contribution  to  the  Morphology  and  Biology 
of  the  Stentors.  Journal  of  Morphology,  vol.  VIII,  no.  3.  Boston, 
U.  S.  A.,  Ginn,  August  1893.  P.  499. 


Posthumous  Action  of  the  Nucleus 


57 


sive,  which  the  nucleus  was  exerting  at  the  moment  of  its 
excision  or  shortly  before. 

We  can  suppose,  as  we  shall  see  better  later,  that  this 
posthumous  action  of  the  nucleus  ("Nachwirkung")  may 
be  explained  in  the  following  way :  Each  of  the  different 
nervous  currents  which  the  nucleus  can  discharge  simul- 
taneously or  successively  into  the  protoplasm  deposits  in 
it,  of  all  the  nuclear  substances  just  that  one  which  had 
given  origin  to  it,  perhaps  by  reproducing  it  partially 
while  on  its  way.  This  substance  once  deposited  in  the 
protoplasm,  would  act  as  a  reserve  which,  while  incapable 
of  growth  by  itself  because  it  lies  outside  the  nucleus, 
would  nevertheless  preserve  for  a  time,  until  its  gradual 
exhaustion,  the  capacity  of  producing  the  same  current 
again.  It  would  produce  in  relation  to  the  excision  of  the 
nucleus,  the  same  effect  as  would  be  produced  by  a  very 
slow  propagation  of  the  respective  current  through  the 
protoplasm.31 

Therefore  one  can  easily  understand  how  in  Gruber's 
experiment,  in  which  the  adoral  ciliated  zone  of  the  an- 
imal was  already  in  an  advanced  stage  of  formation,  the 
whole  series  of  simultaneous  or  successive  formative 
stimuli  had  been  already  discharged  shortly  before  the 
excision  of  the  nucleus,  and  that  therefore  it  remained 
only  to  await  the  slow  unfolding  of  their  effects,  which 
would  bring  to  completion  the  development  already  far 
advanced. 

"Compare  the  partly  similar,  partly  different  hypothesis  of  Ver- 
worn  on  the  posthumous  action  ("Nachwirkung")  of  the  nucleus, 
which  may  be  attributed  to  a  reserve  material  built  up  gradually 
by  the  nucleus  and  given  off  to  the  protoplasm,  and  persisting  till 
the  protoplasm  is  used  up,  in  the  above  mentioned  article:  Die  phy- 
siologische  Bedeutung  des  Zellkerns,  P.  90;  also:  Die  Bewegung 
der  lebendigen  Substanz.  Jena,  Fischer.  1892. 


58    Indications  of  a  Central  Zone  of  Development 

To  one  or  other  of  these  conclusions,  either  to  the 
presence  of  an  undetected  micronucleus  or  to  the  pos- 
thumous action  of  the  nucleus,  one  is  necessarily  driven, 
as  we  said,  by  the  fact  that  only  the  nucleated  fragments 
of  an  infusorian  already  completely  developed,  are  capable 
of  regeneration.  For  this  capacity  of  reorganization, 
as  one  may  call  it,  of  the  protoplasmic  substance, 
which  gives  to  it  again  the  form  of  the  complete 
individual  but  of  correspondingly  smaller  size,  cannot 
possibly  arise  either  from  the  properties  of  this  sub- 
stance itself  or  from  its  specific  "physiological  units"  for 
which  the  adult  form  of  the  individual  would  constitute 
the  only  state  of  equilibrium.  This  is  quite  impossible 
because  a  mass  of  protoplasm  as  large  as  the  nucleated 
part,  but  which  contains  no  nucleus,  does  not  manifest  the 
slightest  tendency  to  regenerate,  although  it  is  capable  of 
surviving  its  ablation  for  several  days.  The  impulse 
tending  to  produce  the  specific  form  of  the  ordinary 
equilibrium  is  present  only  when  the  nucleus  is  not 
lacking. 

Nevertheless  the  material  which  disposes  itself  in  this 
definite  specific  form  of  equilibrium  is  not  the  nuclear  ma- 
terial but  the  protoplasmic.  The  nuclear  substance  with- 
out participating  itself  in  the  process  of  reorganization, 
merely  provokes  it  in  the  protoplasmic  substance,  which  in 
this  respect  remains  totally  indifferent.  This  is  dem- 
onstrated among  other  things  by  the  observation  of 
Gruber  that  the  four  nucleated  fragments  into  which  one 
individual  was  cut  by  a  transverse  and  a  longitudinal  in- 
cision required  in  all  cases  the  same  time  to  regain  their 
complete  specific  form  including  the  adoral  ciliated  zone. 
The  anterior  end  which  already  contained  a  portion  of  it 
and  which  one  would  suppose  to  be  better  adapted  in  its 


Unicellular  Organisms  Like  Pluricellular  59 

protoplasm  to  this  new  formation  requires  just  as  long 
as  the  posterior  end  remote  from  the  adoral  zone.32 

This  impulse  to  reorganization  which  enables  proto- 
plasmic substance  already  organized  to  take  on  any  other 
organization  whatever  speaks  strongly  in  favor  of  the 
hypothesis  that  it  is  due  to  a  special  formative  energy 
("formgestaltenden  Energie"  as  Nussbaum  would  call  it) 
emanating  from  the  nucleus,  which  using  the  proto- 
plasmic substance  merely  as  a  support  or  vehicle  or  as  an 
indifferent  constructive  material,  would  be  in  reality  the 
only  quiddity  which  tends  to  dispose  itself  in  that  partic- 
ular form,  which  constitutes  for  it  the  only  possible 
system  in  dynamic  equilibrium.  For  the  reasons  above 
stated  we  must  think  that  this  formative  energy  is  prob- 
ably nervous  in  nature. 

This  ontogenetic  function  of  the  nucleus  which  we  see 
in  unicellular  organisms  permits  of  very  important  deduc- 
tions in  relation  to  all  organisms  whatever.  For  the  com- 
plicated unicellular  organisms  whose  manifold  organs 
have  different  and  mutually  independent  functions,  such 
as  for  example  a  Stentor  coereleus  or  a  Paramoecium 
caudatum,  are  not  essentially  different  from  pluricellular 
organisms,  but  on  the  contrary  are  comparable  with  them 
in  all  essential  respects. 

"Between  the  internal  differentiations  of  a  complex 
cell,"  says  Delage,  "and  so  between  the  body  of  certain 
Infusoria,  and  the  organs  of  the  pluricellular  being  there 
exists  I  think  only  a  casual  difference,  which  depends  not 
so  much  on  the  requirements  of  the  differentiation  as  on 
the  size  of  the  organism."  33 

82Gruber :  Uber  kunstliche  Teilung  bei  Infusorien.  Zweite 
Mitteilung.  Biol.  Centralbl.,  Bd.  V.  No.  5;  May  i.  P.  138. 

3aDelage:  L'heredite  et  les  grands  problemes  de  la  biologic  gen- 
erale.  P.  97. 


60    Indications  of  a  Central  Zone  of  Development 

"However  great,"  says  Whitman  quoting  Gruber  "the 
difference  between  an  infusorian  and  a  highly  organized 
animal  it  cannot  be  a  qualitative  one.  We  can  assume 
that  the  same  vital  elements  serve  in  both  as  the  founda- 
tion, only  in  ever  new  combinations.  This  kinship 
declares  itself  very  clearly  in  the  correspondence  of  many 
organs  of  the  Infusoria  with  those  of  the  higher  or- 
ganisms. We  mention  only  the  membranellae  of  the 
Infusoria  which  are  quite  similar  to  the  corner  cells  of 
the  mollusk  Cyclas  cornea."  34 

But  we  have  already  seen  that  when  one  cuts  the 
infusorian  into  several  nucleated  fragments  the  membra- 
nellae can  be  formed  from  any  given  part  of  the  proto- 
plasm of  the  original  individual,  and  can  be  arranged  in 
definite  relation  to  one  another  under  the  influence  of  the 
nucleus  as  a  center  from  which  the  formative  activity  of 
the  entire  organism  radiates.  It  is  then  probable  that  the 
formation  and  manner  of  disposition  of  the  corner  cells 
of  the  mollusk  Cyclas  cornea  may  be  due  also  to  a  similar 
process  of  centroepigenetic  nature.  But  this  justifies  us 
in  suspecting  that  in  all  pluricellular  organisms  whatso- 
ever, every  formative  process  commencing  with  normal 
ontogeny  is  of  centroepigenetic  nature. 

This  hypothesis  is  supported  for  example  by  the  ex- 
periments of  King  upon  regeneration  in  Asteria  vulgaris. 
These  have  given  among  others  the  following  results : 
each  of  the  arms  cut  off  close  to  the  body  can  remain  liv- 
ing by  itself  for  two  weeks  but  is  incapable  of  regenerat- 

34Whitman :  The  Inadequacy  of  the  Cell-Theory  of  Development. 
Biol.  Lect.  at  the  Mar.  Biol.  Lab.  of  Wood's  Holl,  Summer  Session 
1893;  Boston  U.  S.  A.,  Ginn,  1894.  P.  118;  and  Journal  of  Morphol- 
ogy, Boston  U.  S.  A.,  August  1893.  Vol.  VIII,  No.  3,  P.  651— 
652;  Fig.  2  and  3. 


Regenerations  Indicate  Central  Zone  61 

ing  the  entire  animal.  If  a  fifth  part  of  the  body  disc 
remains  regeneration  can  occur  in  exceptional  cases.  If 
half  of  the  disc  is  present  the  absent  parts  are  always 
reformed. 

If  one  amputates  all  five  arms  of  the  same  animal  by 
five  transverse  cuts,  the  first  one  very  near  the  body,  the 
others  at  four  different  distances  from  it,  then  after  a 
certain  time, — the  same  for  all  five  arms, — the  regen- 
erated portion  is  largest  for  the  first,  and  proportionately 
smaller  for  the  other  four  according  as  the  site  of  amputa- 
tion was  farther  from  the  central  disc. 

This  regenerated  part  which  has  developed  from  the 
amputated  arm  is  much  smaller  in  diameter  than  the 
original  arm  which  was  cut  off.  That  is  an  indication 
that  the  regeneration  is  not  produced  by  the  cooperation 
of  all  the  parts  immediately  adjacent  to  the  surface  of 
amputation.35 

These  experiments  thus  seem  to  indicate  a  distinct 
zone  from  which  the  process  of  regeneration  proceeds 
and  to  the  activity  of  which  it  is  due. 

From  another  side  the  existence  of  this  formative 
central  zone  is  almost  required  by  the  results  of  the 
similar  experiments  of  Roux,  which  we  have  mentioned 
above,  on  the  formation  of  half  embryos  of  frogs. 

These  experiments  show,  in  brief,  that  each  half,  right 
or  left,  anterior  or  posterior,  can  develop  independently. 
If  one  admits  also  that  this  development  is  always  en- 
tirely epigenetic  in  nature,  that  is  that  it  is  due  entirely  to 
correlative  differentiations  which  the  cells  produce  in  one 

35Helen  Dean  King:  Regeneration  in  Asteria  vulgaris.  Arch.  f. 
Entwicklungsmech,  d,  Org.,  Band,  7.  Heft.  2.  and  3.  Leipzig,  Engel- 
mann.  October  18,  1898.  P.  351—361.  Table  VIII,  especially 
Fig.  ii. 


62    'Indications  of  a  Central  Zone  of  Development 

another,  it  follows  that  at  least  each  quarter  of  the 
embryo  must  have  its  own  system  of  correlation  networks 
independent  of  the  other  quarter  systems.  But  the  four 
quadrants  have  one  zone  which  is  common  to  all.  Con- 
sequently at  least  these  four  independent  systems  of  cor- 
relation networks  for  the  four  quadrants  must  come  off 
from  this  common  zone. 

This  suffices  to  warrant  the  statement  that  this  latter 
must  belong  to  a  central  zone  of  development,  in  the  sense 
which  we  have  set  forth  above;  and  that  from  this  zone 
must  branch  off  and  diverge  independently  of  one  another 
the  different  great  correlation  networks  or  principal 
branches  for  the  general  distribution  of  nervous  energy. 
These  latter  divide  further  into  progressively  smaller 
ramifications,  one  could  almost  say  just  as  the  great 
arterial  trunks  coming  off  from  the  heart  continually  sub- 
divide down  to  the  terminal  capillary  vessels. 

It  is  nevertheless  advisable  to  study  these  phenomena 
more  closely.  We  must  postulate  that  each  of  the  two 
blastomeric  nuclei  obtained  in  the  frog's  egg  after  the  first 
segmentation,  when  it  once  becomes  completely  isolated, 
is  capable  of  giving  rise  to  a  complete  embryo.  But  in 
the  experiments  of  Roux,  the  disposition  of  the  nutritive 
yoke  or  deutoplasm  in  the  uninjured  blastomere  remains, 
thanks  to  the  retention  of  its  place  by  the  injured  blasto- 
mere, the  same  as  the  disposition  which  would  have 
existed  in  this  same  blastomere  if  development  had  pro- 
ceeded normally.  Therefore,  of  all  the  specific  potential 
energies  which  the  uninjured  blastomeric  nucleus  would 
be  capable  of  activating  successively,  there  would  com- 
mence and  continue  to  be  activated  only  those  which  in 
normal  development  would  have  flowed  directly  into  the 


Interpretation  of  Partial  Formations  63 

half  of  the  egg  affording  such  a  definite  deutoplasmic 
disposition. 

So  it  becomes  clear  that  when  once  the  development 
of  the  uninjured  half  of  the  egg  has  commenced,  the 
central  zone  concerned,  even  though  it  may  be  exactly  the 
same  as  in  the  complete  embryo,  would  activate  only  the 
specific  potential  energies  proper  to  the  corresponding 
half  embryo  and  would  produce  only  a  half  formation. 

This  half  formation  no  matter  how  independent  the 
great  correlation  networks  might  be,  could  nevertheless 
at  each  instant  of  its  development,  render  the  system  of 
nuclear  actions  and  reactions  an  incomplete  one,  without 
equilibrium,  because  at  the  plane  of  separation  there 
would  not  be  opposed  to  its  own  nervous  tensions  any 
equivalent  system  of  tensions  of  the  absent  half.  This 
incomplete  system  of  nuclear  tensions,  not  of  itself  in 
equilibrium,  could  nevertheless  be  prevented,  even  though 
only  transiently,  from  equilibrating  itself  normally,  by 
the  special  distribution  of  the  nutritive  yolk  and  by  the 
presence  of  the  injured  half  of  the  egg,  still  placed  op- 
posite that  which  is  developing.  But  as  soon  as  the  con- 
tinual increase  of  energy  in  the  nuclear  system  overcomes 
these  artificial  barriers,  equilibrium  is  once  for  all  upset 
and  postgeneration  will  appear. 

It  is  necessary  nevertheless  to  note  that  some  demi- 
monsters  which  proceed  almost  to  the  completion  of  their 
development  would  seem  on  the  contrary  to  indicate  for 
this  incomplete  system  of  nuclear  actions  and  reactions  a 
practical  equilibrium  existing  from  the  commencement 
and  persisting  through  all  the  stages  of  development. 
The  typical  example  of  these  demimonsters  is  the  famous 
Hemitherium  anterius  which  Roux  so  thoroughly 
describes.  It  is  constituted  by  the  almost  fully  developed 


64    Indications  of  a  Central  Zone  of  Development 

foetus  of  a  half-calf,  in  which  all  the  posterior  part  of 
the  trunk  was  missing  as  if  it  had  been  removed  by  a 
transverse  cut.36 

However  that  may  be,  one  fact  which  speaks  in  favor 
of  the  hypothesis  that  the  nutritive  yolk  acts  as  a  tem- 
porary dam  to  a  system  of  nuclear  actions  and  reactions 
not  of  itself  of  equilibrium,  is  that  these  half  embryos  can 
be  obtained  only  from  those  eggs  in  which,  as  in  the 
Amphibia  and  Ctenophera,  the  nutritive  yolk  is  abundant. 
Whereas  in  the  case  of  animals  whose  eggs  are  poor  in 
nutritive  yolk,  and  present  cleavage  cells  that  are  almost 
identical,  as  in  the  Echinodermata  and  Ascidiae,  either  a 
complete  organism  develops  at  once  from  the  isolated 
blastomere  or  postgeneratiqn  appears  very  early.37 

Another  fact  which  speaks  in  favor  of  this  hypothesis 
is  that  toward  the  end  of  a  spawning  period  when  the 
vitality  of  the  egg,  and  consequently  also  of  the  blasto- 
meric  nuclei,  is  lower,  the  formation  of  pure  half 
embryos  is  much  easier  to  effect.38 

While  thus,  after  exclusion  of  pre formation  theories 
one  can  say  that  the  formation  of  half  embryos  is  a  direct 
proof  of  the  hypothesis  of  a  centroepigenesis  with  its 
ramifying,  independent  correlation  networks,  this  hypoth- 

86Wilhelm  Roux :  Uber  die  kiinstliche  Hervorbringung  ,,halber" 
Embryonen  etc.  Virchows  Archiv,  Bd.  114.  Oct.  i838.  P.  132. 
Gesamm.  Abhandl.  Zw.  Bd.  P.  442. 

37Wilhelm  Roux:  Uber  das  entwicklungsmechanische  Vermogen 
der  beiden  ersten  Furchungszellen  des  Eies.  Verhandlungen  der 
Anat.  Gesellsch.  Wien,  1892.  P.  55—56.  Gesamm.  Abhandl.  Zw. 
Bd.  P.  809—810. 

38Wilhelm  Roux:  Die  Methoden  zur  Hervorbringung  halber 
Froschembryonen  und  zum  Nachweis  der  Beziehung  der  ersten 
Furchungsebenen  des  Froscheies  zur  Medianebene  des  Embryo. 
Anatomischer  Anzeiger,  Bd.  IX.  February  1894.  P.  257.  Gesamrn. 
Abhandl.  Zw.  Bd.  P.  954. 


Development  of  Parts  Not  Due  to  Local  Relations  65 

esis  becomes  confirmed  indirectly  by  a  whole  series  of 
other  facts  which  Roux  also  has  described  and  commented 
upon  with  his  customary  carefulness. 

Natural  or  artificial  headless  monsters  for  example, 
and  in  general  all  monsters  lacking  entire  parts  but  other- 
wise normal,  prove  that  no  formative  action  or  reaction 
is  exerted  by  the  head  or  by  these  other  parts  upon  the 
rest  of  the  organism. 

They  speak  therefore  in  favor  of  a  centroepigenesis 
with  independent  networks  of  correlation  in  which  it  is 
necessary  to  suppose  that  the  formative  action  must 
stream  out  entirely  from  a  center  toward  the  periphery. 
In  all  these  monsters  of  which  some  part  is  lacking,  there 
need  be  present  only  one  part  of  the  body  namely  the  seat 
of  the  central  zone  of  development. 

Roux  in  his  researches  upon  the  formation  of  half- 
embryos  once  observed,  as  an  example  of  the  disturbance 
of  correlations  of  mass  by  the  absence  of  one  embryonal 
half,  a  lateral  dislocation  of  the  notochord  and  a  corre- 
sponding retardation  of  development  of  the  dorsal  part  of 
the  endoblast  lying  near  the  median  line  as  marked  by  the 
semi-medulla  and  by  the  ventral  parts.  "It  is  an  interest- 
ing fact/'  he  remarks,  "that  the  axial  parts  can  be  laid 
down  and  developed  with  so  considerable  a  shifting  in 
relation  to  one  another.  For  this  indicates  further  that 
the  development  of  many  parts  even  of  the  main  parts  is 
not  included  in  the  form  as  such;  the  embryo  does  not 
live  a  formal  life."  39  These  facts  would  also  confirm  the 
hypothesis  of  independent  networks  of  correlation,  the 
displacement  of  whose  material  would  not  alter  their 

39Wilhelm  Roux:  Uber  die  kiinstliche  Hervorbringung  halber 
Embryonen  etc  Virchows  Archiv.  Bd.  114.  October  1888.  P.  132. 
Gesamm.  Abhandl.  Zw.  Bd.  P.  442. 


66    Indications  of  a  Central  Zone  of  Development 

respective  formative  capacity,  because  it  would  leave  un- 
altered the  reciprocal  relations  of  the  different  parts  in 
each  network. 

Further,  the  deformations  which  the  entire  organism, 
and  consequently  also  each  of  its  different  networks, 
undergo,  would  not  seem  to  alter  markedly  the  internal, 
reciprocal  relations  of  the  different  parts  of  each  net- 
work; thus  from  frog's  eggs  which  had  been  compressed 
continuously  during  their  development,  the  blastula  and 
gastrula  having  been  forcibly  flattened,  folded,  and  bent, 
there  developed  embryos  whose  internal  and  external 
aspect  was  just  the  same  as  though  they  had  been  allowed 
from  the  first  to  develop  in  a  normal  fashion  and  had 
undergone  the  deformation  only  later.40 

"In  the  development  of  frog's  eggs  it  happens  very 
often,"  Roux  writes  further,  "that  the  primitive  mouth 
of  the  gastrula  is  not  yet  closed  when  the  medullary  folds 
appear,  and  this  condition  can  persist  in  part  up  till  the 
time  of  the  closure  of  the  medullary  tube  and  the  forma- 
tion of  the  branchial  elevations  and  adhesion  cups.  The 
formation  of  these  latter  can  proceed  in  a  manner  which 
appears  quite  normal  in  the  anterior  half  of  the  body  even 
though  the  posterior  half  of  the  body  may  have  quite  an 
abnormal  form,  the  primitive  mouth  remaining  persist- 
ently wide  open.  Another  instance,  yet  more  surprising, 
is  that  in  which  notwithstanding  the  entire  absence  of  the 
medullary  ridges,  the  gastrula  gradually  exchanges  its 
round  form  for  a  pear  shaped  one,  a  thing  which  or- 
dinarily occurs  only  after  the  formation  and  development 

40Wilhelm  Roux :  Uber  die  ersten  Teilungen  des  Froscheies  und 
ihre  Beziehungen  zu  der  Organbildung  des  Embryo.  Anatomischer 
Anzeiger,  Band  VIII.  1893.  N.  18.  P.  608—609.  Gesamm.  Abhandl. 
Zw.  Bd.  P.  926. 


Anachronisms  Show  Local  Relations  Inessential  67 

of  the  medullary  tube.  These  modes  of  behavior  and 
others  like  them  indicate  that  the  parts  which  continue  to 
develop  normally  require  for  their  development  neither 
the  absent  parts,  nor  that  the  remaining  parts  should  be 
at  the  stage  of  development  normally  corresponding,  and 
thus  that  they  can  develop  alone,  independent  to  a  cor- 
responding extent  of  those  absent  or  backward."  41 

"Anachronisms  of  development,"  continues  Roux  in 
a  later  research,  "appear  also  in  the  relative  retardation 
or  acceleration  of  development  of  one  of  the  germ  layers 
in  relation  to  the  others.  For  example  several  embryos 
otherwise  normal,  in  which  the  medullary  fold  is  still 
quite  undifferentiated,  show  already  in  the  mesoderm,  in 
the  entoderm,  and  in  the  chorda  dorsalis,  formations 
which  appear  normally  only  about  the  time  of  closure  of 
the  medullary  tube.  In  this  case  there  is  an  evident  re- 
tardation of  development  of  the  ectoderm  in  relation  to 
the  development  of  the  other  two  layers.  There  occur 
also  inequalities  of  lesser  degree  in  the  rapidity  of 
development  of  the  two  lateral  halves  of  the  body,  and 
thus  it  is  possible  to  observe  two  different  stages  of 
development  in  the  same  object."  42 

"If  such  large  parts  of  the  organism,"  concludes  our 
author  in  a  still  later  study,  "can  remain  behind  in  their 
development  or  indeed  remain  absent,  without  thereby 
producing  any  disturbance  in  the  development  of  the 
others,  it  follows  surely  that  the  development  of  these 

"Wilhelm  Roux:  Zur  Orientierung  fiber  einige  Probleme  der 
embryonalen  Entwicklung.  Zeitschrift  fur  Biologic.  Bd.  XXI. 
Miinchen,  Jul  1885.  P.  478—479.  Gesamm.  Abhandl.  Zw.  Bd.  P. 
203—204. 

42Wilhelm  Roux:  Uber  die  kunstliche  Hervorbringung  halber 
Embryonen,  usw,  Virchows  Archiv,  P.  128 — 129.  Gesamm.  Abhandl. 
Zw.  Bd.  P.  438. 


68    Indications  of  a  Central  Zone  of  Development 

latter  is  not  at  all  bound  up  by  reciprocal  actions  with  the 
absent  parts,  and  also  that  it  is  not  accomplished  by  the 
reciprocal  action  of  parts  of  the  whole  organism." 43 
These  conditions  are  just  those  existing  in  a  centro- 
epigenesis  with  ramifying  and  independent  networks  of 
correlation. 

The  formation  of  double  monsters  with  double 
symmetry  in  the  disposition  of  their  organs  is  particularly 
in  accord  with  centroepigenesis.  Concerning  this  Roux 
expresses  himself  in  this  way:  "In  these  double  forma- 
tions the  fragment  which  is  lacking  in  a  symmetrically 
similar  manner  from  each  of  the  two  individuals,  can  be 
any  selected  piece  limited  by  a  plane  surface ;  and  in  them 
the  organs  are  nearly  all  present  and  normal  in  form  up 
to  the  plane  of  union,  as  if  from  two  embryos,  fully 
developed  and  ready  to  be  born,  one  had  cut  off  two 
symmetrical  pieces  so  as  to  leave  plane  surfaces,  and  the 
twins  had  then  been  reunited  by  the  cut  surfaces."  "The 
simultaneous  development  of  two  formations  so  exten- 
sively united,  into  two  distinct  bodies,  of  which  each  is 
centered  in  itself,  indicates  directly  that  there  are  not  any 
general  reciprocal  actions  operating  to  combine  them  into 
a  single  whole."  44 

According  to  the  centroepigenetic  hypothesis,  the 
formation  of  these  monsters  would  be  due  to  the  fact  that 
the  two  blastomeres  concerned,  which  are  quite  identical 
with  each  other  since  they  arise  from  the  segmentation  of 
one  and  the  same  egg,  have  become,  on  account  of  ab- 

48Wilhelm  Roux:  Uber  Mosaikarbeit  und  neuere  Entwicklungs- 
hypothesen.  Anat.  Hefte,  Edited  by  Merkel  and  Bonnet,  Febru- 
arheft  1893.  P.  320.  Gesamm.  Abhandl.  Zw.  Bd.  P.  859. 

44Wilhelm  Roux:  Uber  Mosaikarbeit  etc.  Anat.  Hefte,  P.  320. 
Gesamm.  Abhandl.  Zw.  Bd.  P.  859—860. 


Centroepigenesis  Accords  with  General  Phenomena  69 

normal  circumstances  which  have  made  them  independent 
of  each  other,  two  distinct  nodal  points, — two  central 
zones  of  development.  The  necessary  consequences  of 
the  independent  action  of  these  two  centers  of  develop- 
ment would  be  the  centration  of  each  individual  by  itself. 
On  the  other  hand,  the  similarity  of  the  two  first  blasto- 
meric  nuclei,  which  through  multiplication  give  rise  to 
both  of  the  two  central  zones  concerned,  would  bring 
about  a  similarity  of  the  formative  actions  given  off  from 
these  zones.  Therefore  those  formative  stimuli  which 
act  upon  all  points  of  any  one  of  the  infinite  number  of 
planes  symmetrical  in  relation  to  these  centers,  would 
offset  and  annul  one  another,  because  they  would  be 
equal  and  opposite  but  only  in  so  far  as  they  do  act 
along  these  planes.  In  this  way  could  be  explained  why 
the  parts  lacking  in  both  individuals  must  always  be  alike. 

While  thus  all  these  different  facts  which  have  at- 
tracted the  careful  attention  of  Roux  and  been  made  the 
special  object  of  his  studies  confirm,  some  directly  others 
indirectly,  the  hypothesis  of  centroepigenesis  with  ram- 
ifying and  independent  networks  of  correlation,  a  further 
support,  indirect  indeed,  but  nevertheless  very  real,  will 
be  brought  forward  in  the  following  chapter.  For  we 
shall  endeavor  there  to  show  that  if  a  whole  series  of 
facts  compels  us  to  throw  over  preformation,  a  series  of 
other  facts  forces  us  to  throw  over  simple  epigenesis  also, 
and  this  would  give  a  high  degree  of  probability  to  any 
other  hypothesis  with  which  both  series  of  facts  should 
be  in  accord. 

Finally,  the  symmetrical  disposition  which  the  greater 
number  of  organisms  present  in  relation  to  a  point,  to  a 
straight  line,  or  to  a  plane,  and  also  the  advance  of 
growth  along  diverging  ramifications,  which  indeed  is  a 


70    Indications  of  a  Central  Zone  of  Development 

general  law  of  organic  development,  are  phenomena 
which  indicate  in  their  turn  that  this  centroepigenesis 
with  ramifying,  independent  networks  for  the  distribu- 
tion of  nervous  energy,  is  also  in  harmony  with  the  most 
general  biologic  phenomena. 

One  could  always  bring  forward  the  objection  that  it 
is  difficult  to  conceive  how  this  series  of  energies  acting 
one  after  the  other,  all  upon  the  same  point  of  the  de- 
veloping organism,  could  give  rise  to  a  series  of  dynamic 
systems  of  distributions  as  complex  as  we  must  neces- 
sarily suppose  those  to  be  which  constitute  the  successive 
stages  of  ontogeny.  To  dissipate  all  doubts  in  this  mat- 
ter one  may  draw  attention  to  the  following  simple 
hydro-dynamic  experiment. 

Let  us  imagine  a  very  large  cylindrical  glass  container 
almost  filled  with  water,  and  having  a  hole  at  a  selected 
point  in  the  bottom  of  it.  By  means  of  a  suitable  force 
pump  let  us  make  more  water  enter  the  vessel  through 
this  hole  with  a  velocity  varying  from  one  moment  to 
another.  To  make  the  idea  clear  and  the  phenomenon 
more  intelligible  let  us  suppose  that  the  velocity  varies 
sharply  each  second,  sometimes  increasing,  sometimes 
diminishing  very  considerably.  On  account  of  the  great 
amount  of  water  already  contained  in  the  vessel,  the 
series  of  successive  systems  of  very  complex  currents 
which  will  be  produced  each  moment  by  the  incoming 
water,  whose  newly  added  mass  interpenetrates  and  dis- 
places the  other  in  a  manner  which  we  can  make  appar- 
ent in  part  by  previously  coloring  the  water  to  be  injected, 
will  depend  on  the  entire  series,  and  exclusively  on  the 
series,  of  different  velocities  with  which  the  water  is 
forced  into  the  container. 

A  given  series  of  dynamic  actions,  qualitatively  alike 


Centroepigenesis  in  Plants  71 

but  quantitatively  different,  starting  successively  always 
from  the  same  point  could  thus  give  rise  to  a  succession 
of  dynamic  systems  of  as  complex  a  configuration  as  one 
could  imagine.  Different  series,  that  is  to  say  those  in 
which  quantitative  variations  of  the  same  dynamic  ac- 
tion succeed  one  another  in  different  ways,  would  natur- 
ally give  rise  also  to  dynamic  systems  of  different 
configuration. 

We  can  compare,  though  only  roughly,  this  water 
which  enters  the  container  always  by  the  same  opening 
and  with  a  velocity  changing  every  instant,  to  the  series 
of  nervous  currents  of  different  specificity  which,  accord- 
ing to  our  hypothesis,  would  be  discharged  into  the  soma 
in  the  course  of  development,  or  into  the  great  mass  of 
yolk,  by  the  activity  of  the  germinal  substance,  always 
from  one  and  the  same  point  of  the  organism,  which 
would  thus  constitute  the  central  zone  of  development. 

It  would  be  proper  at  this  point  to  touch  upon  the 
probable  location  of  this  central  zone.  But  important  as 
it  is  we  do  not  need  to  stop  long  over  it. 

It  is  necessary  at  the  outset  to  notice  in  a  very  general 
way  that  in  plants,  and  especially  in  the  higher  plants, 
one  must  regard  the  leaf  as  the  true  individual  and  one 
must  attribute  to  it  a  centroepigenesis  of  its  own.  The 
flower  would  then  be  merely  the  product  of  numerous 
centroepigeneses  not  entirely  independent  of  one  another : 
The  corresponding  simultaneous  or  rapidly  successive 
activations  of  multiple  centers,  and  the  reciprocal  action 
of  these  centers  upon  one  another,  would  be  indeed  the 
agents  by  which  modifications  of  each  of  the  centro- 
epigeneses is  effected,  so  as  to  produce  for  example  here 
a  petal  and  there  a  pistil  instead  of  an  ordinary  leaf. 

It  would  also  be  possible  for  a  center  or  a  definite 


72    Indications  of  a  Central  Zone  of  Development 

group  of  these  centers,  perhaps  on  account  of  some 
special  situation,  to  become,  in  the  course  or  at  the  end  of 
the  particular  centroepigenesis  producing  the  different 
parts  of  the  flower,  and  in  relation  to  all  the  other  centers 
and  so  to  the  whole  flower,  the  director  to  a  further  de- 
velopment; so  that  there  would  be  present  for  the  whole 
development  of  the  flower,  or  for  a  part  of  it  at  least,  a 
centroepigenesis  of  the  second  degree. 

By  analogy  one  can  conceive  also  of  the  possibility  of 
other  centroepigeneses  of  still  higher  degrees  (composite 
flowers,  etc.). 

"It  may  appear/'  writes  Le  Dantec,  "that  the  sexual 
individual  belongs  to  a  higher  order  than  the  asexual  in- 
dividual and  may  originate  from  the  individualization  of 
an  association  of  parts  which  are  like  asexual  individuals* 
It  occurs  perhaps  in  the  Medusae ;  it  is  certain  in  Phane- 
rogams. A  flower  corresponds  morphologically  to  an 
assemblage  in  a  fixed  form,  of  parts  which  are  like  the 
asexual  individuals  of  the  plant.  Goethe  had  already 
noted  this  peculiarity.  The  asexual  individual  of  a  plant 
is  the  internode  with  its  leaf  and  auxiliary  bud :  flowers 
are  much  more  complex."  45 

Centroepigeneses  of  a  second  or  higher  grade  could 
thus  serve  to  explain  the  transformation  of  simple  colonies 
of  individuals,  (e.  g.,  of  the  ancestors  of  the  present 
echinoderms),  into  complicated  organisms,  which  tend 
steadily  toward  an  individualization  of  their  own.  One 
could  explain  easily  the  transformation,  for  example,  of 
the  original  individuals  of  the  colony,  becoming  more  and 
more  differentiated  from  one  another,  into  the  organs  of 
this  organism  (siphonophores).  With  the  growth  of 

"Le  Dantec:  Traite  de  Biologic.    Paris,  Alcan,  1903,  P.  413. 


Location  and  Structure  of  the  Central  Zone      73 

centralization  (annelids,  arthropods),  centroepigeneses  of 
the  second  or  higher  degrees  would  approximate  grad- 
ually more  and  more  the  simple  centroepigeneses  of  the 
first  degree. 

"The  gastrula,"  adds  Le  Dantec  further,  "itself  a 
morphologic  unit  of  higher  order  than  the  cell,  can  itself 
bud  off  other  gastrulas,  just  as  the  cell  can  produce  other 
cells  by  budding.  This  budding  may  take  place  always  in 
the  same  direction  and  so  give  rise  to  linear  associations 
of  gastrulas,  as  in  the  worms,  arthropods,  etc. ;  or  it  may 
take  place  in  every  direction  and  thus  produce  plant- 
like  associations,  for  example  the  fibroid  polyps  or  coral 
polyps;  it  may  proceed  radially  and  so  give  rise  to  the 
echinoderms.  Even  the  vertebrates  themselves  would  be, 
according  to  this,  the  result  of  an  individualized  assem- 
blage of  a  linear  series  originally  comparable  with  an 
annelid  worm.  That  is  the  theory  of  human  polyzoism  of 
Durand  de  Gros  and  Edmond  Perrier."  4G 

After  what  has  been  said  thus  far  the  probable  loca- 
tion of  the  central  zone  of  development  of  the  various 
types  of  organisms  need  not  be  especially  treated  of  here. 

The  place  in  which  we  must  suppose  it  to  be,  which 
naturally  lies  in  the  plane  of  symmetry  of  the  organism, 
appears  almost  self  evident  from  what  we  have  said 
above,  and  will  become  steadily  clearer  from  what  will  be 
said  in  continuation.  It  may  here  be  remarked  merely 
that  this  zone  cannot  be  imagined  as  any  special  tissue 
marked  off  distinctly  from  the  surrounding  somatic  tis- 
sues ;  but  must  rather  be  a  simple,  indistinguishable  part 
of  some  tissue  whose  special,  somatic  functions  in  the 
adult  individual  are  such  as  predispose  it  best,  in  the 

40Le  Dantec :   Traite  de  Biologic.     P.  412. 


74    Indications  of  a  Central  Zone  of  Development 

descendant  organism,  to  the  definite  function  of  develop-- 
ment,  and  which  differentiates  itself  gradually  from  the 
other  parts  of  this  tissue  by  quite  inappreciable  and 
gradual  transitions. 

We  have  already  said  that  the  centroepigenetic 
hypothesis  makes  it  necessary  to  distinguish  the  effective 
germinal  zone,  or  true  place  of  origin  of  the  germinal 
substance,  from  the  apparent  germinal  zone,  which  would 
be  nothing  else  than  the  receiving  station  for  the  sub- 
stance separated  out  or  secreted  by  the  effective  germinal 
zone,  or  the  place  where  the  sexual  cells  concerned  are 
built  up  out  of  this  material.  While  we  must  regard  only 
the  effective  germinal  zone  as  the  central  zone  of  develop- 
ment, it  is  clear  that  the  apparent  germinal  zone  can  be 
located  at  any  part  whatever  of  the  organism. 

In  the  higher  plants  the  apparent  germinal  zone  of  the 
asexual  budding  cells,  and  that  of  the  female,  sexual  cells, 
would  seem  generally  to  coincide  approximately  with  the 
actual  zone,  that  is,  with  the  corresponding  central  zone 
of  the  leaf  and  of  the  flower. 

In  this  way  can  be  explained  the  heretofore  puzzling 
phenomenon  of  the  Xenia,  in  which  as  is  known  the 
flower  after  a  hybrid  fecundation,  often  takes  on  the 
form,  size,  color  and  tissue  structure,  characteristic  of  the 
variety  from  which  the  pollen  comes ;  that  is,  as  Darwin 
has  already  observed  "in  which  the  male  element  not 
only  influences  the  germ  as  is  its  proper  function,  but 
at  the  same  time  influences  various  parts  of  the  mother 
plant,  in  the  same  manner  as  it  influences  the  same  parts 
in  the  seminal  offspring  from  the  same  two  parents."  4T 

47Darwin :  The  Var.  of  Animals  and  Plants  under  Domestication. 
Eighth  impression  of  the  second  edition.  Vol.  I.  London,  Murray, 
1882.  Chap.  XI,  P.  433. 


Determination  of  Location  of  Central  Zone       75 

In  the  pluricellular  animals  we  can  start  out  with  the 
simple  supposition  that  if  a  central  zone  of  development 
is  present,  it  is  probably  that  in  which  the  blastomeres 
multiply  with  unlike  rapidity ;  that  is,  it  will  be  constituted 
by  these  blastomeres  which  multiply  most  rapidly.  For 
this  greater  rapidity  would  in  the  majority  of  cases 
indicate  a  greater  vitality  or  energy,  which  may  be 
produced  by  a  richer  protoplasm  or  by  any  other  special 
condition  favoring  the  nutrition.  And  this  greater 
energy  would  bring  it  about  that  the  cells  possessing  it 
would  win  the  upper  hand  over  the  others. 

"The  zone,"  writes  Oscar  Hertwig,  "where  the 
smallest  embryonal  cells  lie,  which  are  also  those  which 
divide  most  rapidly,  becomes  the  place  of  gastrular 
invagination ;  it  becomes  something  like  a  fixed  center  of 
crystallization  for  the  animal  development."  48  But  these 
blastomeres  are  those  which,  in  the  vertebrates  for 
example,  later  constitute  the  medullary  tube  and 
afterward  the  spinal  cord. 

As  we  shall  see,  everything  seems  to  lead  to  the  con- 
clusion that  in  animals  with  specialized  nervous  systems 
the  central  zone  is  constituted  by  the  least  differentiated 
part  of  the  nervous  system  itself;  in  the  vertebrates 
probably  by  the  innermost  periependymal  part  of  the 
spinal  cord.  This  part  after  completion  of  its  activity  in 
determining  development  would,  on  account  of  the  so- 
matic function  pertaining  to  it,  likewise  constitute  the 
place  where  the  infinitely  manifold  nervous  activities  of 
all  the  rest  of  the  nervous  system  or  rather  of  the  whole 
organism  are  faintly  re-echoed. 

As  we  have  already  said,  this  location  of  the  central 

48Oscar  Hertwig:  Zeit-  und  Streitfragen  der  Biologic.  Heft.  2. 
Mechanik  und  Biologic.  Jena,  Fischer,  1897.  P.  180. 


76      Hypothesis  of  Structure  of  Germ  Substance 

zone  is  almost  self-evident  from  what  has  preceded,  and 
will  be  still  more  so  from  what  is  to  follow.  Here  it  may 
only  incidentally  be  remarked,  (since  we  have  treated  of 
the  subject  more  thoroughly  in  another  place),  that  this 
hypothesis  concerning  the  location  of  the  central  zone  in 
vertebrates,  and  in  general  in  those  animals  which  have 
a  specialized  nervous  system,  finds  a  very  strong  support 
also  in  the  numerous  researches  and  observations  upon  the 
influence  which  the  nervous  system  exercises  upon  de- 
velopment and  regeneration.49 

From  this  we  can  now  pass  on  to  the  discussion,  even 
though  very  briefly,  of  the  question  of  the  probable  com- 
position and  structure  of  the  substance  which  constitutes 
this  zone,  and  which  is  consequently  none  other  than  the 
germinal  substance.  This  affords  an  opportunity  of 
speaking  of  the  not  essential  but  subordinate  difference  by 
which  the  germinal  nuclei  are  probably  distinguished  from 
the  somatic. 

2.     Hypothesis    Upon    the  Structure    of   the   Germinal 

Substance 

We  have  seen  that  according  to  the  centroepigenetic 
hypothesis,  ontogeny  can  be  attributed  to  a  series  of  mod- 

"See  e.  g.  Wolff:  Die  physiologischcn  Grundlagen  der  Lehre 
von  den  Degenerationszeichen.  Virchows  Archiv,  Bd.  164,  1902; — 
Richard  Rubin :  Versuche  iiber  die  Beziehung  des  Nervensystems  zur 
Regeneration  bei  Amphibien.  Archiv  f.  Entw.-Mech.  d.  Org.,  Bd. 
XVI,  Heft  i ;  March  13,  1903 ; — Kurt  Goldstein :  Kritische  und  ex- 
perimentelle  Beitrage  zur  Frage  nach  dem  Einflu/3  des  Zentralner- 
vensystems  auf  die  embryonale  Entwicklung  und  die  Regeneration. 
Arch,  fur  Entw.-Mech.  d.  Org.,  Bd.  XVIII,  Heft  i;  February  26, 
1904; — Eugenio  Rignano:  Die  zentroepigenetische  Hypothese  und  der 
Einflu/3  des  Zentralnervensystems  auf  die  embryonale  Entwicklung 
und  die  Regeneration,  Arch.  f.  Entw.-Mech.  d.  Org.,  Bd.  XXI,  Heft. 
4;  September  u,  1906 


Composed  of  Specific  Potential  Elements         77 

ifications  in  the  general  distribution  of  nervous  energy 
of  the  organism.  If  we  consider  the  law  of  Haeckel  in 
its  first  degree  of  approximation,  we  must  suppose  as  we 
have  already  said,  that  this  distribution  of  nervous  energy 
constitutes  by  itself  at  each  ontogenetic  stage  a  system  in 
dynamic  equilibrium,  because  the  same  distribution  of 
this  energy  was  in  equilibrium  in  the  corresponding  an- 
cestors. To  provoke  the  transition  from  one  dynamic  sys- 
tem to  the  other,  it  is  necessary  that  at  each  ontogenetic 
stage  there  become  active  in  the  central  zone  a  new  spe- 
cific energy,  which  disturbs  the  dynamic  equilibrium 
which  has  just  been  formed  and  effects  the  transition  to 
a  new  dynamic  equilibrium. 

This  leads  to  the  supposition  that  the  germinal  sub- 
stance may  be  constituted  by  a  number  of  material  par- 
ticles of  which  each  would  be  able  to  activate  only  the 
corresponding  specific  nervous  energy.  We  can  desig- 
nate each  of  these  particles  by  the  term  specific  potential 
element. 

We  must  here  provisionally  postulate  the  possibility 
that  there  may  be  substances  capable  of  containing  in  the 
respective  potential  condition,  not  only  definite  forms  of 
energy  but  also  different  specific  modes  of  the  same  form 
of  energy.  We  shall  take  up  the  question  again  later  in 
order  to  make  it  clearer  and  to  handle  it  more  thoroughly. 
It  may  be  remarked  here,  however,  that  a  chemical  analy- 
sis of  the  material  particles  of  the  nucleus,  which  actually 
contain  the  hereditary  mass,  could  hardly  throw  much 
light  upon  the  eventual  differentiation  of  the  different  ma- 
terials which  compose  the  entire  germinal  substance. 
For,  at  least  for  the  moment,  it  can  give  only  the  com- 
position of  the  possibly  homogeneous  residue  into  which 


78      Hypothesis  of  Structure  of  Germ  Substance 

all  these  different  substances  break  up  or  decompose  as 
soon  as  life  has  gone  out  of  them. 

In  conformity  with  the  views  of  most  biologists,  we 
can  assume  that  the  hereditary  mass,  and  therefore  all 
the  specific  potential  elements,  are  preserved  and  distrib- 
uted during  what  is  called  the  resting  stage,  in  the  gran- 
ules of  chromatin  which  are  disposed  like  the  beads  of  a 
rosary  upon  the  nuclear  reticulum ;  but  during  mitosis,  in 
the  chromosomes,  and  particularly  in  the  little  discs  of 
chromatin  which  the  chromatic  filaments  into  which  the 
nuclear  reticulum  and  its  granules  contract,  often  present, 
superimposed  upon  one  another  and  separated  by  inter- 
vening layers  of  linin. 

We  must  nevertheless  note  that  this  mode  of  dispo- 
sition of  the  different  specific  potential  elements  in  the 
nucleus  is  of  importance  to  us  only  in  relation  to  nuclear 
division.  For  we  must  hold  with  the  epigenesists,  as  we 
shall  see  soon,  that  this  division  always  proceeds  in  a 
manner  qualitatively  the  same. 

But  this  disposition  is  of  absolutely  no  importance  to 
us  in  relation  to  the  effects  which  it  will  have  upon  the 
serial  activation  of  these  elements.  From  this  latter 
point  of  view  we  can  indeed  suppose  these  elements  to 
be  scattered  through  the  germinal  nucleus  and  mixed 
with  one  another  in  any  way  whatever. 

For,  as  we  shall  see  better  later,  the  activation  of 
every  specific  potential  element  in  the  proper  ontogenetic 
stage,  depends  in  no  way  upon  its  position  in  relation  to 
the  others,  but  rather  on  the  condition  that  at  this  stage 
only  its  activation  requires  the  doing  of  only  a  moderate 
amount  of  work — an  amount  which  does  not  require  more 
energy  than  the  total  quantity  inherent  in  each  element. 
Its  activation  in  any  other  stage  would  require,  on  ac- 


Nuclear  Somatization  and  Equal  Cell  Division    79 

count  of  the  much  greater  modification  which  it  would 
then  induce  in  the  distribution  of  nervous  energy  already 
existing,  the  doing  of  a  large  amount  of  work, — an 
amount  which  would  require  more  energy  than  the  quan- 
tity present  in  each  element. 

The  centroepigenetic  hypothesis  of  a  single  limited 
zone  containing  the  germinal  substance,  and  the  other 
conception  following  upon  it,  that  the  germinal  sub- 
stance may  consist  of  a  number  of  different,  material 
particles,  each  representing  one  particular,  specific,  poten- 
tial element  brings  up  the  question  of  nuclear  somatiza- 
tion. 

We  postulate  the  existence  of  a  central  germinal  zone 
distinct  from  the  soma.  We  must  not  forget  neverthe- 
less that  all  nuclei  arise  by  division  from  the  first,  that 
of  the  egg.  If  we  also  admit  with  the  epigenesists  a 
qualitatively  equal  nuclear  division,  then  the  nuclei  des- 
tined to  become  somatic  must  at  first  be  equivalent  with 
those  destined  to  become  the  central  zone  of  development. 
In  what  way  then  is  the  nuclear  somatization  brought 
about  in  the  cells  which  later  must  constitute  all  the  dif- 
ferent tissues  of  the  body? 

There  presents  itself  at  once  the  preliminary  ques- 
tion: Must  we  really  admit  this  nuclear  division  to  be 
always  qualitatively  equal  ?  Or  shall  we  rather  hold  with 
the  preformists  that  in  addition  to  equal  nuclear  divi- 
sions there  may  be  also  unequal  divisions  ?  On  this  point 
we  believe  we  ought  to  agree  unconditionally  with  the 
epigenesists. 

There  does  not  exist  any  observation  which  gives  even 
the  slightest  ground  for  the  conclusion  that  there  is  a 
qualitatively  unequal  division.  "By  the  most  thorough 
study  of  the  longitudinal  division  of  the  chromosomes," 


8o      Hypothesis  of  Structure  of  Germ  Substance 

writes  Strassburger,  "it  is  absolutely  impossible  to  hunt 
out  anything  but  equal  division.  Unequal  division  is  not 
presented  at  all.  There  is  not  a  single  fact  to  support  the 
notion  that  it  exists."  50 

We  shall  here  limit  ourselves  to  mentioning  only  two 
orders  of  facts  which  speak  directly  against  unequal  divi- 
sion: 

First,  it  does  not  occur  in  any  nucleus  in  the  vast  realm 
of  unicellular  and  of  primitive  pluricellular  forms,  con- 
sisting of  colonies  of  like  cells;  for  in  them  the  facts  of 
heredity  show  directly  that  nuclear  division  is  always 
equal. 

But  especially  the  oft  repeated  and  keenly  discussed 
experiments  upon  the  relative  shifting  and  isolation  of 
blastomeres  afford  direct  proof  that  nuclear  division  is 
equal  in  the  first  segmentations  of  the  egg.  We  recall  for 
example  the  experiments  of  Chabry  upon  the  Ascidians, 
those  of  Wilson  upon  Amphioxus,  those  of  Herbst  on  the 
separation  of  the  blastomeres  of  the  sea  urchin  merely  by 
adding  chloride  of  potassium  to  ordinary  sea  water,  of 
Driesch  on  the  Echinus  microtuberculatus,  of  Oscar  Hert- 
wig  upon  frogs'  eggs,  of  Raffaello  Zoja  on  the  Medusae 
and  so  on.  These  experiments  in  which  one  of  the  first 
blastomeres,  or  one  of  the  four,  or  eight,  or  sixteen,  or 
thirty-two  first  blastomeres,  produce  when  isolated  an 
entire  embryo,  perfectly  formed  but  proportionally 
smaller,  or  in  which  the  blastomeres,  though  shuffled 
about  in  any  way  whatever,  nevertheless  developed  in  a 
perfectly  normal  way,  lead  with  the  greatest  certainty 
that  any  one  could  desire  to  the  conviction  that  in  the 

BOStra/3burger :  Uber  periodische  Reduktion  der  Chromosomen- 
zahl  im  Entwicklungsgang  der  Organismen.  Biol.  Centralbl.,  XIV. 
No.  23-24.  Leipzig,  Dec.  i,  and  15,  1894.  P.  835. 


Cell  Division  Hereditarily  Equal  81 

successive  blastomeric  divisions  the  nuclei  always  remain 
like  the  first,  that  of  the  egg  from  which  they  sprung. 

The  contrary  cases  of  the  formation  of  half  embryos, 
or  of  incomplete  embryos,  after  the  separation  or  killing 
of  one  of  the  two  first,  or  of  several  of  the  first  blasto- 
meres,  are  found  always  and  only  in  embryos  rich  in 
deutoplasm,  so  that,  as  we  have  already  seen,  they  cannot 
afford  any  ground  for  the  conclusion  that  the  nucleus  or 
nuclei  from  which  these  incomplete  embryos  develop  must 
be  different  from  the  first  nucleus,  that  of  the  egg. 

We  shall  examine  in  the  following  chapter  the  very 
complex  and  untenable  subsidiary  hypotheses,  to  which 
the  partisans  of  unequal  division  have  been  driven,  in 
order  to  bring  their  principal  hypothesis  into  accord  with 
experiments  upon  the  isolation  and  displacement  of 
blastomeres,  and  also  with  other  equally  irreconcilable 
processes,  such  as  post-generation  and  regeneration.  Here 
we  shall  only  quote  and  adopt  the  conclusion  which  Oscar 
Hertwig  has  drawn  from  these  experiments,  namely :  "It 
is  self-evident  that  such  an  interchange  of  blastomeres 
without  injury  to  the  product  of  development,  is  possible 
only  if  one  nucleus  has  the  same  characters  as  the  others, 
that  is,  only  if  all  the  nuclei  are  produced  from  the  seg- 
mentation nucleus  by  hereditarily  equal  division."  51 

In  order  that  this  hereditarily  equal  division  may  be 
materially  possible  in  a  germinal  nucleus  constituted  by 
innumerable,  different,  infinitely  small  particles, — that  is 
in  order  to  permit  the  division  of  each  of  these  particles 
or  substances  between  the  two  daughter  nuclei, — it  would 
be  sufficient  that  they  become  disposed  during  mitosis  in 
little  transverse  layers  one  over  another  in  the  various 

"Oscar  Hertwig :   Die  Zelle  und  die  Gewebe.    Zw.  Buch.    P.  69. 


82      Hypothesis  of  Structure  of  Germ  Substance 

little  discs  of  chromatin  of  the  chromatic  filament,  in 
exactly  the  same  disposition  as  that  which  these  little 
discs  actually  do  present  in  the  chromatic  filament. 

Admitting  then  that  nuclear  division  is  always  quali- 
tatively equal  we  must  now  ask:  does  this  really  mean 
that  the  nuclei  of  all  cells  must  remain  alike  throughout 
the  whole  of  development? 

But  before  taking  up  this  question  we  must  first 
answer  a  preliminary  one :  must  we  exclude  nuclear  som- 
atization  with  the  epigenesists  or  admit  it  with  the  pre- 
formists  ? 

If  it  seemed  to  us  impossible  to  disagree  with  the 
epigenesists  upon  the  first  question  of  a  qualitatively  equal 
nuclear  division,  it  seems  on  the  contrary  impossible  to 
disagree  with  the  preformists  on  this  second  of  a  nuclear 
somatization.  We  shall  certainly  not  repeat  here  all  the 
arguments  by  which  these  latter  support  their  thesis. 
They  can  be  summed  up  in  their  essential  parts  in  the 
following  words  of  Weismann. 

"The  chromatin  is  able  to  imprint  upon  the  cell  in 
the  nucleus  of  which  it  lies  a  specific  character.  Just  as 
the  thousands  of  cells  which  make  up  the  organism 
possess  very  different  characters  and  very  different 
functions,  so  the  chromatin  which  controls  them  cannot 
be  every  where  alike,  but  must  rather  be  different  in 
different  kinds  of  cells."  52 

The  epigenesists,  on  the  contrary,  are  well  known 
to  be  inclined  to  the  view  that  all  the  somatic  cells  of 
the  organism  have,  without  distinction,  like  nuclei  con- 
stituted by  the  same  idioplasm.  Oscar  Hertwig  indeed 
ventures  the  assertion  that  each  somatic  cell  if  it  were 

"Weismann:  Das  Keimplasma,  eine  Theorie  der  Vererbung. 
Jena,  Fischer,  1892.  P.  43  and  268. 


Cells  Become  Differentiated  and  Somatized       83 

possible  to  put  it  in  conditions  which  would  render  it 
capable  of  nourishing  itself  and  preserving  its  life 
independently  separated  from  the  rest  of  the  organism, 
could  function  as  a  germ  cell.53 

And  certain  processes  which  appear  in  all  the  lower 
organisms,  with  tissues  that  are  not  very  highly 
specialized,  appear  to  justify  this  view. 

If  one  places  a  piece  of  a  Begonia  phyllomaniaca  in 
some  earth  in  moist  air,  after  cutting  through  the  leaf- 
ribs  in  different  places,  one  finds  after  some  time,  in  the 
neighborhood  of  each  wound,  one  or  more  little  new 
plants.  Any  fragment  whatever  of  a  hydra  or  medusa 
possesses  the  power  of  reforming  an  entire  animal 
without  increasing  its  mass,  but  rather  by  a  process  of 
differentiation  and  rearrangement  of  cells  already  existing. 

A  theory  which  admits  equal  nuclear  division  and  also 
a  slow  and  gradual  nuclear  somatization,  resulting  from 
the  action  of  a  determinate  zone  constituted  only  by  the 
germinal  substance,  would  reconcile  the  different  and 
contradictory  phenomena  brought  forward  by  the  epi- 
genesists  on  the  one  side,  and  by  the  preformists  on  the 
other. 

Oscar  Hertwig  who  as  we  have  just  seen  is  a  zealous 
partisan  of  the  idioplasmic  equality  of  all  nuclei,  is  com- 
mitted in  another  place  to  the  possibility  of  a  certain 
nuclear  somatization.  "The  hypothesis  of  a  hereditarily 
equal  nuclear  division  does  not  imply  the  view  that  the 
'anlage'  substance  must  therefore  be  an  immutable 
thing.  .  .  .  The  idioplasms  of  certain  groups  of  cells 
of  an  organism  which  find  themselves  permanently  in 
unlike  conditions  in  consequence  of  their  different  spatial 
and  functional  disposition  in  the  body  as  a  whole,  dif- 

"Oscar  Hertwig:  Die  Zelle  und  die  Gewebe.  Zw.  Buch.  P, 
304—305. 


84      Hypothesis  of  Structure  of  Germ  Substance 

ferentiated  as  it  is  through  the  division  of  labor,  can 
receive  to  a  certain  extent  the  stamp  of  local  character."  54 

If  we  admit  that  each  new  specific  current  while 
passing  through  a  nucleus  deposits  there  the  substance 
which  was  capable  of  producing  it,  and  which  would  be 
capable  on  occasion  of  reproducing  this  same  specific 
current, — a  hypothesis  of  which  we  reserve  a  better 
exposition  till  later, — we  can  conceive  of  nuclear  soma- 
tization  as  a  gradual  and  constant  acquisition  of  new, 
specific,  potential,  somatic  elements. 

The  fact  that  each  cell,  as  long  as  its  differentiation 
has  not  progressed  too  far,  can  upon  occasion,  provided 
it  be  isolated  from  its  neighbors,  arise  to  the  rank  of  a 
germinal  cell,  appears  to  indicate  that  these  new  somatic 
elements,  thus  gradually  acquired,  would  from  the  start 
be  simply  added  to  the  germinal  elements  already  existing, 
without  altering  them  at  all,  but  merely  relegating  them 
to  the  potential  state,  from  which,  under  normal 
conditions,  they  would  not  again  emerge. 

In  other  terms  we  must  suppose  that  all  the  germinal 
elements  remain  unaltered  in  the  nuclei  undergoing 
somatization  as  long  as  the  number  or  the  mass  of 
acquired  somatic  elements  does  not  progress  beyond  a 
given  limit. 

But  when  this  limit  is  once  passed,  then  the  require- 
ments of  nutrition  or  of  space  would  cause  the  different 
germinal  elements  to  disappear  gradually,  and  the  nucleus 
concerned  would  thus  lose  all  generative  capacity. 

Further  even  those  somatic  elements,  which  each 
nucleus  acquired  one  after  another  at  each  successive 
stage  of  development,  will  gradually  disappear  after 

"Oscar  Hertwig :  Zeit-  und  Streitfragen  der  Biologic.  Praforma- 
tion  oder  Epigenese?  Jena,  Fischer,  1894.  P.  142 — 143. 


How  Somatization  Reduces  Germinal  Capacity    85 

ontogeny  is  completed,  for  then  the  nuclei  are  always 
exposed  to  one  specific  current  or  to  a  limited  group  of 
specific  currents  peculiar  to  the  adult  state.  There  would 
remain  over  only  a  small  or  very  inconsiderable  number 
of  those  somatic  elements  which  were  acquired  last  and 
which  would  thenceforth  continually  increase  in  mass. 
The  cell  would  thus  lose  by  degrees  its  undifferentiated 
embryonic  aspect,  and  its  exclusively  somatic  characters 
would  steadily  increase. 

While  according  to  Weismann  there  would  be  a 
fundamental  distinction  between  the  germinal  nuclei  set 
apart  for  the  preservation  of  the  entire  hereditary  mass, 
and  the  somatic  nuclei  which  from  the  first  would  receive 
only  such  particles  of  that  hereditary  mass  as  are  indis- 
pensable for  their  function,  and  the  ontogenetic  passage 
from  one  to  the  other  would  take  place  suddenly  and 
directly  at  the  very  commencement  of  development; 
according  to  the  centroepigenetic  hypothesis,  on  the 
contrary,  there  would  not  exist  any  essential  difference 
between  them,  because  they  differ  from  each  other  only 
in  the  number  and  the  specificity  of  their  respective 
potential  elements,  and  the  passage  from  one  to  the 
other  would  be  effected  gradually  and  slowly.  And  this 
transition  would  be  due  we  repeat  only  to  the  constant 
acquisition  by  the  nuclei  destined  to  become  somatic,  of 
new  specific  potential  elements,  which  at  first  are  simply 
added  to  the  germinal  elements  already  present  but  finish 
by  causing  the  latter  gradually  to  disappear  on  account 
of  the  requirements  of  nutrition  and  space  and  by  taking 
their  place  themselves. 

Without  needing  to  have  recourse  to  a  reserve 
idioplasm,  or  to  any  other  equally  involved  subsidiary 
hypothesis,  one  can  explain  in  this  way  the  phenomena, 


86      Hypothesis  of  Structure  of  Germ  Substance 

common  in  plants,  of  the  retention  by  some  cells  of  the 
germinal  capacity  even  though  they  belong  to  somatic 
tissues  which  have  already  advanced  to  a  certain  degree 
of  differentiation. 

In  the  same  way  is  easily  explained  how  a  given 
piece  of  a  hydra  or  medusa  reorganizes  itself  so  as  to 
reproduce  the  entire  individual  without  any  correspond- 
ing increase  of  its  mass. 

For  since  histologic  differentiation  in  the  hydra  is 
not  very  pronounced  one  can  surmise  a  priori  that  in 
all  or  nearly  all  their  cells,  the  whole  of  the  specific 
potential  elements  must  coexist  with  the  somatic  elements 
peculiar  for  each  cell  and  acquired  by  it  during  develop- 
ment. The  separation  of  the  fragment  from  all  the  rest 
of  the  organism,  which  arrests  the  general  circulation 
of  nervous  energy,  will  therefore  cause  the  somatic 
elements  which  were  active  in  the  intact  individual  to 
return  to  the  exclusively  potential  state  and  thus  enable 
the  germinal  elements  to  become  active  again.  That 
cell  or  group  of  cells  which  surpasses  the  others  in  vigor 
will  have  its  germinal  elements  activated  first  and  will 
then  form  a  central  zone  directing  development  of  the 
others;  and  the  distribution  of  nervous  energy,  which 
again  passes  through  the  wonted  series  of  ontogenetic 
stages,  will  now  proceed  in  the  fragment  in  the  same 
way  as  formerly  in  the  entire  individual. 

There  are  often  external  circumstances  which  deter- 
mine what  cells  of  the  fragment  shall  constitute  the  central 
zone.  Thus  if  one  cuts  off  from  the  trunk  of  the  hydra 
both  the  tail  end  and  the  head  end  at  the  same  time, 
and  then  places  the  fragment  with  the  lower  cut  surface 
down,  the  head  is  reproduced  at  the  same  end  as  formerly, 
whereas  if  one  turns  it  over  so  that  the  former  head  end 


More  Vigorous  Cell  Groups  Direct  Development  87 

of  the  polyp  sticks  into  the  sand  of  the  aquarium,  the 
head  is  reproduced  at  the  aboral  pole. 

Sometimes  two  distinct  groups  of  cells  seem  to 
struggle  with  each  other  to  constitute  the  central  zone 
of  development,  and  both  may  attain  their  object  thus 
producing  double  monsters.  If  from  the  trunk  of  a 
hydra  one  cuts  off  at  the  same  time  both  the  tail  and 
the  head  end,  and  suspends  the  fragment  horizontally 
in  the  water  it  forms  a  head  at  both  ends. 

In  an  analogous  way,  Morgan  in  his  experiment  on 
the  regeneration  of  Planar ia  maculata  once  obtained 
from  a  fragment  which  had  been  cut  off  by  two  trans- 
verse sections,  two  heads  one  at  the  front  end,  the  other 
at  the  hind  end.55 

This  simultaneous  activation  of  two  centers  of  develop- 
ment can  go  on  also  at  the  commencement  of  ontogeny 
in  the  cells  of  the  blastula  itself.  "From  causes  which 
are  yet  beyond  our  knowledge,  there  are  often  produced 
(in  fish  eggs)  two  gastrular  imaginations  instead  of 
one,  at  separate  points  of  the  blastula.  And  it  depends 
on  the  position  of  these  two  invaginations,  which  could 
also  be  designated  crystallization  centres  for  the  further 
development  of  the  embryos,  how  the  embryonic  cells 
of  the  germinal  disc  are  then  drawn  into  the  process  of 
development,  given  very  definite  positions  in  relation  to 
one  another,  and  utilized  for  the  formation  of  organs."  56 

The  analogous  phenomena  of  heteromorphosis  in 
general  can  likewise  be  explained,  through  the  similar, 


65 Morgan :  Experimental  Studies  on  the  Regeneration  of  Plan- 
aria  maculata.  Arch.  f.  Entwicklungsmech.  d.  Org.  Bd.  VII.  2  and 
Heft,  3.  Leipzig,  Engelman.  Oct.  18,  1898.  P.  381,  395. 

B6Oscar  Hertwig:  Zeit-  und  Streitfragen  der  Biologic.  Prafor- 
mation  oder  Epigenese?  P.  60 


88      Hypothesis  of  Structure  of  Germ  Substance 

abnormal  activation  of  new  centres  of  development  after 
amputations,  incisions,  or  in  any  other  abnormal  condi- 
tions whatever  in  the  most  different  regions  of  the  organ- 
ism which  otherwise  would  have  continued  to  constitute 
definite  somatic  parts  of  it. 

In  Planaria  maculata  for  example  these  new  develop- 
mental centers  of  heteromorphous  formations,  of  which 
this  animal  affords  perhaps  the  most  typical  cases,  appear, 
according  to  the  results  of  recent  researches,  to  be  formed 
always  from  one  of  the  two  ends  of  the  piece  of  the 
lateral  nerve  tract  which  is  separated  by  the  operation 
from  the  other  parts  of  this  tract.57 

Indeed  it  appears  to  be  indicated  by  these  latest  and 
most  careful  researches  that  those  pieces  of  the  planar ian 
which  contain  no  part  of  this  nerve  tract  are  not  able 
to  regenerate  themselves,  any  more  than  are  those  frag- 
ments of  infusoria  which  contain  no  part  of  the  nucleus.58 

Therefore  this  animal  forms  perhaps  the  transition 
from  those  pluricellular  organisms  in  which  all  the  somatic 
cells  preserve  throughout  their  capacity  of  regeneration 
undiminished,  to  those  in  which  this  capacity  exists  in 
the  adult  in  only  a  very  definite  and  special  zone. 

The  phenomenon  which  more  than  any  other  speaks 
in  favor  of  a  nuclear  somatization  arising  in  the  higher 
multicellular  organisms  during  development,  is  the  cir- 
cumstance that  the  capacity  of  regeneration  diminishes 
with  age;  for  it  is  very  much  greater  in  embryos  than 
in  fully  developed  animals.  For  example,  if  the  feet  of 
an  adult  frog  are  cut  off,  they  do  not  grow  again,  whereas 

"Charles  Russell  Bardeen :  Factors  in  Heteromorphosis  in  Plan- 
ariae.  Arch.  f.  Entwicklungsmech.  d.  Org.  Bd.,  XVII.  i.  Heft.  13 
March  1903.  P.  1—20,  esp.  P.  6—8;  Fig.  5,  6,  7. 

"Charles  Russell  Bardeen :  Ibid.    P.  2,  3. 


Transformations  Show  Epigenetic  Socialization   89 

Barfurth  has  demonstrated  that  during  the  first  stages 
of  development  this  regeneration  is  complete.  And  Roux 
has  found  that  if  one  cuts  quite  young  frog  embryos 
into  longitudinal  or  antero-posterior  halves  the  missing 
parts  are  completely  regenerated  in  a  few  hours.59 

On  the  other  hand,  if  the  regeneration  of  the  optic 
lens  in  the  triton  from  a  tissue  other  than  that  from 
which  it  is  developed  in  ontogeny,  is  of  itself  enough 
to  exclude  preformation  decisively,  it  is  nevertheless  not 
in  any  way  incompatible  with  the  most  complete  nuclear 
somatization.  If  one  admits  this  latter,  the  histological 
transformation  of  certain  cells  would  indicate  only  the 
possibility  that  in  certain  ways  somatized  nuclei  may 
become  differently  somatized,  if  unusual  influences  are 
exerted  upon  them  by  neighboring  nuclei,  that  is  if 
nervous  energies  other  than  the  usual  ones  act  upon 
them;  and  they  would  undergo  this  new  somatization 
through  the  gradual  acquisition  of  new  specific,  potential 
somatic  elements,  different  from  the  former  ones.  By 
itself  this  transformation  certainly  does  not  prove  that 
all  nuclei  of  the  different  cells  consist  of  like  idioplasm. 

Further  there  is  no  firm  support  for  this  supposed 
idioplasmic  identity  of  the  nuclei  in  the  researches  deal- 
ing with  vegetable  and  animal  grafts. 

In  order  to  support  such  a  hypothesis  effectively, 
these  investigations  would  have  to  show  a  closer  relation- 
ship or  "harmonicity"  (as  Vochting  would  say)  between 
different  tissues  of  the  same  individual  or  of  individuals 
belonging  to  the  same  species,  than  between  like  tissues 

"Roux:  Uber  die  verschiedene  Entwicklung  isolierter  erster 
Blastomeren.  Arch.  f.  Entwicklungsmech.  der  Organismen,  1895, 
Band,  I.  Heft  4.  P.  614. 


90      Hypothesis  of  Structure  of  Germ  Substance 

of  different  species.  But  this  demonstration  has  not 
been  afforded  in  a  single  instance  of  animal  grafting. 

There  are  indeed  examples  of  transfusion  of  blood 
which  do  not  succeed  when  they  are  made  from  one 
animal  to  another  of  different  species,  whereas  they  do 
succeed  perfectly  between  animals  of  the  same  species. 
There  are  the  experiments  of  Bert  upon  the  successful 
transplantation  of  a  fragment  of  the  tail  of  a  mouse 
into  the  subcutaneous  tissue  at  another  part  of  the  body 
of  the  same  individual  or  of  another  individual  of  the 
same  or  a  related  species,  as  Mus  decumanus  and  Mus 
rattus,  whereas  such  a  transplantation  is  not  successful 
between  species  farther  removed,  such  as  Mus  rattus 
and  Mus  silvaticus.  There  are  the  experiments  of  Oilier 
and  Schmitt  on  the  transplantation  of  fragments  of 
bony  tissue,  which  were  successful  in  transplantations 
from  one  part  to  another  of  the  same  individual  or  to 
another  individual  of  the  same  species,  but  failed  be- 
tween individuals  of  different  species.60 

But  all  these  experiments  indicate  only  that  there  is 
more  affinity  between  the  parts  of  the  same  tissue  or  of 
similar  tissues  when  they  belong  to  individuals  of  the 
same  species  or  of  related  species  than  when  they  are 
taken  from  individuals  of  different  species.  They  do 
not  prove  at  all  that  there  is  more  affinity  between  parts 
of  different  tissues,  which  come  from  the  same  individual 
or  from  individuals  of  the  same  species,  than  between 
parts  of  the  same  tissue  taken  irom  different  species. 

On  the  other  hand  Joest's  experiments  have  demon- 
strated the  possibility  of  true  heteroplastic  grafts  in  the 
annelids,  in  which  it  is  easy  to  obtain  transplantations 

e°Oscar  Hertwig:  Die  Zelle  und  die  Gewebe.     II,  P.  24*?. 


Grafts  Do  Not  Show  Idioplasmlc  Identity        91 

between  different  species.  In  contrast  with  the  results 
obtained  by  Oilier  and  Schmitt,  the  transplantation  to 
man  of  portions  of  bony  tissue  and  of  horny  tissue  which 
were  taken  from  carnivorous  or  rodent  mammals,  has 
been  entirely  successful.  It  is  known  indeed  that  the 
transplantation  of  a  cock's  comb  to  a  cow's  ear  has  been 
successfully  effected.  Born,  in  his  famous  experiments, 
has  succeeded  in  transplanting  definite  parts  of  young 
embryos  of  Rana  esculenta  to  corresponding  parts  of 
other  embryos,  not  only  of  the  same  species  but  also 
of  different  species  (Rana  fusca,  arvalis  and  esculenta), 
and  indeed  of  different  genera  (Rana  esculenta  and 
Bombinator  igneus).  61 

All  these  experiments  show  that  the  plasticity  or 
capacity  of  transformation  of  living  organic  substance 
reaches  much  farther  than  between  individuals  of  the 
same  species.  Therefore  it  cannot  be  explained  by  the 
idioplasmic  identity  of  the  nuclei,  which  in  any  case 
could  exist  only  between  tissues  of  the  same  individual 
and  between  individuals  of  the  same  species. 

There  are  certain  grafts  in  plants  that  appear  to 
justify  the  conclusion  that  there  is  a  single  nuclear 
idioplasm,  identical  throughout  the  whole  plant.  For  in 
grafts  between  plants  of  the  same  species  there  has  even 
been  obtained  the  union  of  parts  which  have  nothing  in 
common  with  each  other  at  all,  as  for  example  a  root 
with  a  leaf.  Whereas  if  one  attempts  to  transplant  even 
in  quite  normal  relations,  parts  of  plants  belonging  to 

"Compare  e.  g.  Oscar  Hertwig:  Die  Zelle  und  die  Gewebe.  II. 
P  23;  Delage:  L'Heredite  etc.  P.  114;  G.  Born:  Uber  Verwach- 
sungsversuche  mit  Amphibienlarven.  Leipzig,  Engelmann.  1897.  P. 


92      Hypothesis  of  Structure  of  Germ  Substance 

different  species  the  result  of  the  graft  is  not  certain 
and  often  unfavorable. 

This  can  be  explained  by  the  fact  that  in  numerous 
species  of  plants,  as  we  have  seen,  nearly  all  the  cells 
preserve  the  reproductive  capacity.  What  one  calls 
"vegetative  affinity"  is  then  perhaps  nothing  else  than 
a  direct  effect  of  the  retention  of  the  whole  of  the 
specific  germinal  potential  elements  in  addition  to  the 
somatic  elements  peculiar  to  each  of  the  different  tissues, 
in  all  or  nearly  all  the  different  nuclei  which  do  not 
pass  beyond  a  certain  degree  of  differentiation. 

In  drawing  a  conclusion  from  all  that  has  been  said 
so  far,  we  are  confronted  with  this  apparent  paradox: 
on  the  one  side,  it  seems  that  in  conformity  with  the 
epigenesists  we  must  reject  a  nuclear  division  which 
during  one  and  the  same  development  must  be 
sometimes  qualitatively  equal,  sometimes  unequal,  as 
inadmissable  and  refuted  by  the  facts,  and  instead  of 
this  admit  only  a  nuclear  division  always  qualitatively 
equal.  On  the  other  hand  it  appears  that  in  conformity 
with  the  preformists,  one  must  likewise  exclude  a  nuclear 
substance,  identical  in  all  the  cells  of  the  same  organism, 
and  must  accept  on  the  contrary,  the  hypothesis  of  an 
actual  nuclear  somatization.  It  follows  that  this  nuclear 
somatization  can  be  effected  only  gradually  and  only  by 
a  process  of  epigenetic  nature. 

But  when  one  has  once  admitted  equal  nuclear  divis- 
ion and  gradual  nuclear  somatization  by  a  process  of 
epigenetic  nature,  there  follows  therefrom  necessarily  the 
hypothesis  of  centroepigenesis.  For  if  the  nuclei  of  the 
cells  of  the  different  tissues  of  the  body  finally  become 
completely  somatized  it  is  certain  that  some  certain  ones 
of  the  nuclei  constituting  the  organism  do  not  become 


Elasticity  of  Developing  Organisms  93 

somatized  at  all,  namely  those  whose  function  it  is  to 
supply  the  reproductive  cells  with  germinal  substance. 
And  if  the  first  nuclei  become  somatized  by  a  process  of 
epigenetic  nature,  this  process  even  though  it  involve  the 
entire  organism,  must  leave  the  other  nuclei  unaltered. 
But  this  would  be  possible  only  when  this  process  is 
dependent  on  influences  proceeding  from  the  zone  of 
germinal  nuclei,  and  being  exerted  by  it  in  such  a  manner 
that  the  germinal  substance  concerned  does  not  become 
altered  at  all. 

The  continuity  of  the  germinal  substance,  the  spec- 
ificity of  the  nuclei,  and  the  epigenetic  nature  of  the 
formative  processes  of  organisms, — these  three  concep- 
tions which  individually  are  favored  by  a  great  number 
of  biologists — imply  together  the  conception  of  centro- 
epigenesis. 

Another  fact  which  has  been  considered  perhaps  less 
than  it  deserves,  supports  the  hypothesis  that  the  process 
of  development  is  not  only  of  epigenetic  nature,  but  also 
depends  upon  influences  coming  off  incessantly  and  suc- 
cessively from  a  point  which  is  external  to  all  the  trans- 
forming parts,  but  which  remains  itself  unchangeable; 
namely  the  elasticity  by  virtue  of  which  developing  organ- 
isms, much  more  than  those  completely  developed,  are 
able  not  only  to  undergo  without  injury  enormous  changes 
of  form  but  also  to  resume  their  original  form  as  soon  as 
the  disturbing  influence  ceases.  And  just  to  this  greater 
elasticity  of  the  young  organism  is  to  be  attributed  the 
fact  that  it  is  much  less  plastic  than  the  adult  organism. 

In  fact  the  centroepigenetic  hypothesis  would  permit 
one  to  deduce  this  a  priori.  For  according  to  it  the 
young  organism  is  so  much  more  elastic,  because  in  it 
all  the  cells,  being  less  specialized,  are  thus  much  more 


94      Hypothesis  of  Structure  of  Germ  Substance 

easily  able  to  assume  any  new  somatic  character  what- 
ever which  may  be  imposed  upon  them.  It  makes  no 
difference  in  the  case  of  the  still  unspecialized  cell,  or 
even  in  that  of  the  cell  which  is  in  the  first  stages  of 
specialization,  whether  the  somatizing  stimulus  is  onto- 
genetic,  proceeding  by  indirect  ways  from  the  central 
zone,  or  functional,  induced  by  the  environment.  For 
the  embryonic  cell  is  in  itself  thoroughly  plastic.  Con- 
sequently the  young  soma  would  also  be  plastic  if 
it  were  not  continually  influenced  by  the  formative  stimuli 
proceeding  from  the  central  zone  of  development.  This 
influence  though  it  is  more  feeble  than  the  functional  stim- 
ulus proceeding  from  the  environment  and  consequently 
unable  to  resist  it,  has  nevertheless  the  advantage  of  be- 
ing continuously  in  action,  and  so  of  gaining  the  ground 
lost,  as  soon  as  the  action  of  the  environment  ceases. 

The  cells  of  the  adult  soma  are  on  the  contrary  less 
plastic,  because  they  are  already  considerably  specialized. 
But  every  modification  which  their  limited  plasticity  per- 
mits in  them  remains,  since  the  opposition  of  the  central 
zone  of  development  has  already  ceased.  The  adult 
organism  is  much  less  elastic.  But  in  respect  to  the 
permanence  of  results  it  is  more  plastic  than  the  young 
one. 

And,  as  already  said,  this  is  entirely  confirmed  not 
only  by  the  most  commonplace  phenomena,  but  also  by 
the  most  careful  embryologic  researches.  In  fact  con- 
siderable changes  of  form,  which  would  be  destructive 
to  an  adult  organism  are,  on  the  contrary,  very  well 
borne  by  the  young.  But  attentive  observation  of  these 
processes  shows  us  also,  as  stated,  that  the  younger  the 
organism  the  greater  is  its  elasticity,  which  tends,  when 
the  disturbing  action  has  ceased,  to  restore  it  to  its 


Roux's  Self  Regulating  Mechanism  95 

primitive  slate.  Thus  it  is  that  a  wound  or  a  fracture 
is  never  so  detrimental  to  the  child  as  to  the  adult;  but 
it  is  also  tnu-  that  with  the  same  intensity  and  duration 
of  the  educative  influence  directed  toward  the  modifica- 
tion of  inborn  tendencies  the  results  are  more  permanent 
the  older  the  child  is. 

This  elasticity  of  development  is  proved  by  Roux 
with  his  customary  care  in  the  following  way. 

In  one  of  his  experiments  on  the  effects  of  passive 
deformations  in  the  first  stages  of  development  he  suc- 
ceeded in  bending  a  few  frogs*  embryos  within  their 
gelatin  envelopes  by  squeezing  them  between  needles.  "If 
the  needles  were  removed  immediately  after  the  deforma- 
tion, the  embryo  at  once  took  on  again  its  previous  form; 
if  they  remained  however  a  few  hours  the  deformation 
tended  to  be  a  persistent  one  and  disappeared  again 
only  in  the  course  of  several  hours;  a  proof  that  an  inter- 
nal adaptation  to  the  new  form  had  already  commenced, 
but  which  was  in  its  turn  caused  to  disappear  in  the 
course  of  further  development,  perhaps  by  the  action  of 
growth  forces  inhibited  during  the  deformation  but  re- 
sumed upon  the  restoration  of  the  normal  form."02 

Roux  gives  this  dynamic  elasticity  of  development 
tin-  name  "mechanism  of  self  regulation."  Let  us  note 
again  that  the  absence  of  this  elasticity  in  adult  organisms, 
which  remain  plastic  in  relation  to  the  somewhat  persist- 
ent, deforming  influences  of  the  environment,  would  de- 
note that  this  mechanism  is  active  only  during  embryonic 
life.  Now  the  continued  action  exercised  by  the  central 
zone  of  development  constitutes  precisely  such  a  mechan- 

"Wilhelm  Roux:  Zur  Orientierung  iiber  einige  Probleme  dcr 
embryonalen  Kntwicklung.  Zeitschr.  f.  Biol.  Bd.  XXI.  Miinchen, 
July  1885.  P,  515—516.  Gesamm.  Abhandl.  Zw.  Bd.  P.  245. 


96      Hypothesis  of  Structure  of  Germ  Substance 

ism  of  self -regulation,  active  during  the  whole  of  onto- 
geny but  ceasing  upon  the  completion  of  development. 

Another  example  of  the  dynamic  elasticity  of  devel- 
opment, no  less  characteristic  in  certain  respects  than  the 
preceding,  has  been  repeatedly  observed  by  Roux  in  the 
postgeneration  of  his  half  embryos.  "In  the  postgenera- 
tion  of  the  mesoblast  it  can  be  observed  that  very  young 
yolk  cells  with  nuclei  not  yet  stainable,  and  also  the  re- 
mains of  substances  not  yet  cellulized,  hinder  the  differen- 
tiation, and  so  divert  the  mesoblastic  formation  toward 
the  interior  or  divide  the  formation  into  two  layers;  but 
after  the  circumvention  of  this  obstacle  the  further  dif- 
ferentiation soon  resumes  its  normal  course ;  a  procedure 
in  its  essence  extremely  puzzling."  es 

It  may  be  merely  noted  here  that  this  elasticity  of  de- 
velopment helps  to  explain  the  interpolation  of  certain 
newer  ontogenetic  formations  or  stages  (placenta  and 
similar  things)  in  the  series  of  older  ontogenetic  stages, 
without  markedly  altering  the  earlier  or  later  members 
or  even  the  last  member  of  this  ancient  series. 

"We  have  reason  to  believe/'  says  Orr,  "that  the  man- 
ner of  growth  for  some  particular  period  of  the  develop- 
ment may  be  secondarily  changed  without  radically  affect- 
ing either  the  preceding  or  succeeding  growth.  As  an  ex- 
ample of  this  may  be  mentioned  the  embryonic  organs  and 
embryonic  modifications  which  adapt  the  embryo  to 
undergo  partial  development  in  the  body  of  the  parent, 
and  allow  it  to  receive  nutriment  from  the  parent,  e.  g. 
the  placenta."  64 

fl3Wilhelm  Roux:  Uber  die  kunstliche  Hervorbringung  halber 
Embryonen  usw.  Virchows  Archiv.  B.d.  114,  October  1888.  P.  276. 
Gesamm.  Abhandl.  Zw.  Bd.  P.  504. 

"Orr:  A  Theory  of  Development  and  Heredity.  New  York, 
Macmillan,  1893.  P.  210. 


Temporarily  Disturbing  Action  of  Yolk  Mass     97 

These  embryonal  organs  and  modifications  which  in- 
terpolate themselves  in  the  series  of  ontogenetic  stages, 
leaving  these  latter  unchanged,  can  then  also  serve  as 
proof  that  developing  organisms  are  elastic  but  not  plas- 
tic, while  contrariwise  grown  organisms  remain  plastic 
but  not  elastic. 

To  these  facts  one  can  add  that  the  large  accumulation 
of  yolk  in  the  egg  cells  exerts  a  great  influence  on  the 
first  stages  of  development,  but  subsequently  exerts  abso- 
lutely no  influence  on  the  other  stages.  "The  organiza- 
tion of  the  egg,"  says  Hertwig,  "which  depends  on  the 
disposition  of  the  deutoplasm,  has  fundamentally  only  a 
subordinate  influence,  and  that  of  a  secondary  and  tran- 
sient nature  in  the  developmental  process."  "Eggs  of  ani- 
mals which  belong  to  different  races  can  present  a  very 
similar  type  of  cleavage  and  similar  early  embryonic 
forms,  while  eggs  from  closely  related  divisions  of  one 
and  the  same  race  divide  in  very  different  ways,  and  dif- 
fer very  extraordinarily  in  the  nature  of  the  blastula  and 
gastrula.  The  deposition  of  yolk  material  in  the  egg  im- 
prints a  quite  characteristic  stamp  upon  the  first  embry- 
onic stages, — the  cleavage  process,  the  blastula,  gastrula 
and  so  on, — but  it  has  no  influence  on  the  essence  of  the 
animal  species  itself,  nor  on  the  formation  of  any  special 
species  of  animal."  65 

One  has  here  then  developments,  which,  altered  in 
the  first  stages  by  the  influence  exerted  by  the  yolk  mate- 
rial, later  resume  their  normal  course,  exactly  as  though 
they  had  undergone  no  alteration.  In  other  words  the 
yolk  substance  alters  the  normal  development  only  tem- 
porarily, only  for  so  long  as  its  action  continues  to  make 

"Oscar  Hertwig :  Die  Zelle  und  die  Gewebe.   II.  P.  265—266. 


98      Hypothesis  of  Structure  of  Germ  Substance 

itself  felt.  This  process  corresponds  essentially  to  that 
described  in  the  above  mentioned  researches  on  the  trans- 
position of  the  blastomeres,  in  which  the  latter  were  com- 
pressed for  example  between  two  plates  and  so  all  com- 
pelled to  lie  in  the  same  plane.  But  when  the  pressure 
ceased  they  resumed  at  once  their  normal  disposition. 
Each  of  these  two  processes  constitutes  another  proof 
of  the  self -regulating  capacity  or  elasticity  of  devel- 
opment which  finds  in  centroepigenesis  its  most  simple 
explanation. 

Centroepigenesis  implies  further,  as  we  have  seen,  that 
the  distribution  of  nervous  energy  in  each  stage  of  de- 
velopment forms  in  itself  a  system  in  complete  dynamic 
equilibrium,  which  becomes  disturbed  and  replaced  by  an- 
other system  in  equilibrium,  only  through  the  activation 
by  the  central  zone  of  a  new  specific  potential  element. 
This  is  the  conception  from  wrhich  as  a  starting  point  we 
have  built  up  our  hypothesis. 

It  follows  that  if  the  activation  of  the  specific  potential 
elements  successive  to  any  given  stage  is  prevented 
through  certain  abnormal  circumstances,  development  will 
stop  without  thereby  causing  the  organism  thus  remain- 
ing behind  in  an  earlier  ontogenetic  stage,  to  cease  to 
form  a  dynamic  system  in  complete  equilibrium. 

Such  transitory  or  permanent  arrests  of  development 
are  extremely  numerous,  much  more  numerous  than  com- 
monly believed.  All  the  phenomena  called  atavistic  rever- 
sion belong  in  this  category.  Metamorphoses  also,  with 
the  exception  of  certain  characteristic  and  remarkable 
phenomena  which  have  been  added  later,  are  only  similar 
arrests  of  development,  which  proceeds  at  once  on  its 
course  as  soon  as  external  conditions,  and  with  them  also 


Atavism  and  Variation  in  Crosses 


99 


the  conditions  within  the  organism,  become  again  favor- 
able to  further  development. 

As  a  typical  example  of  these  arrests  of  development 
may  be  mentioned  the  well  known  case  of  the  aquatic 
salamanders,  (newts).  These  tailed  amphibians  at  a  cer- 
tain stage  of  their  ontogeny  take  to  the  land,  lose  their 
gills,  and  become  accustomed  to  respiration  by  lungs.  If 
however  they  are  prevented  from  doing  that  by  impris- 
onment in  a  closed  aquarium,  they  retain  their  gills,  and 
the  triton  is  halted  for  life  at  a  low  stage  of  development, 
which  its  near  relatives,  the  perennibranchs  never  pass. 

The  hypothesis  of  centroepigenesis,  which  has  thus 
been  derived  in  its  entirety  from  the  fundamental  bio- 
genetic  law  taken  in  its  first  degree  of  approximation,  that 
is  in  the  sense  of  an  exact  repetition  of  phylogeny  by 
ontogeny,  implies  also  that  in  two  species  arising  from  a 
common  ancestor,  the  series  of  specific  potential  elements 
remain  the  same  up  to  the  ontogenetic  stage  corre- 
sponding to  this  common  ancestor,  and  only  after  this 
stage  do  the  series  of  elements  concerned  in  the  two  spe- 
cies diverge  from  one  another. 

It  follows  that  in  crosses  development  can  go  on  very 
well  so  long  as  the  two  series  of  germinal  elements  are 
identical,  but  it  becomes  hindered  as  soon  as  the  elements 
concerned,  which  strive  to  become  active  at  the  same  time, 
thwart  one  another  by  their  difference.  And  through  this 
hindrance  to  development  the  organism  will  take  on  a 
form  similar  to  that  of  the  common  ancestor.  Further  a 
few  germinal  elements  too  feeble  heretofore  in  relation  to 
the  others,  and  therefore  unable  to  become  active  during 
the  development  of  organisms  of  the  pure  strain,  are  able, 
if  common  to  both  races,  to  acquire  by  their  union  a  pre- 
ponderance over  the  others  different  in  the  two  species, 


ioo    Hypothesis  of  Structure  of  Germ  Substance 

and  so  to  secure  the  energy  necessary  to  their  activation, 
and  thus  to  bring  out  in  the  cross  certain  characters  of 
the  ancestor  which  otherwise  would  not  be  found  in  the 
existing  species  in  any  of  its  ontogenetic  stages. 

In  this  way  then,  by  the  arrest  of  development  at  the 
ontogenetic  stage  at  which  the  respective  germinal  ele- 
ments of  the  two  species  begin  to  diverge  from  one  an- 
other, can  be  explained  in  the  most  direct  possible  manner 
the  above  mentioned  phenomena  of  atavistic  reversion 
which  all  hybrids  present. 

"The  offspring  of  a  cross  of  two  such  species,"  writes 
Orr,  "might  therefore  continue  its  development  so  long 
as  the  two  inherited  impulses  were  alike,  but  when  the  im- 
pulses begin  to  impel  growth  in  opposite  directions,  de- 
velopment must  cease.  This  explains  why  the  imper- 
fectly developed  offspring  of  a  crossed  species  resembles 
an  ancestral  form."  66 

For  example  the  distinct,  colored,  transverse  stripes 
on  the  foreleg  and  shoulder  of  the  mule,  which  in  the 
horse  and  the  ass  are  quite  rare  and  usually  very  faint, 
arise  in  this  way  and  must  be  referred  to  the  common  an- 
cestor of  both  species.  From  the  crossing  of  certain  races 
of  pigeons  arise  birds  which  have  the  slate  colored  plu- 
mage of  the  wild  dove,  even  though  the  races  concerned 
in  the  crossing  possess  quite  a  different  color.  But  it  has 
been  proven  that  these  races  branched  off  directly  from 
the  wild  races.  In  the  same  way  the  mixed  breeds  of  do- 
mestic ducks  recall  the  wild  ducks.  And  the  hybrid  of  a 
German  and  Japanese  pig  is  quite  similar  to  a  wild  boar. 
The  hybrids  of  Datura  ferox  and  Datura  laevis  regularly 
have  blue  flowers  instead  of  the  white  of  their  parents ; 

"Orr :    A  Theory  of  Development  and  Heredity.     P.  230—231. 


Activation  of  Last  Element  Ends  Development  101 

and  Darwin  proves  that  this  is  a  reversion  to  a  blue  flow- 
ering ancestor.  The  tendency  to  incubate,  which  domes- 
tic hens  so  often  lose,  always  appears  again  in  their 
hybrids.  The  hybrids  of  ducks  show  a  tendency  to  mi- 
grate. The  mule  is  harder  to  break  thoroughly  than  the 
horse  or  the  ass.67 

These  examples  afford,  in  our  estimation,  the  most 
certain  proof  that  the  ontogenetic  stimuli  of  two  species 
arising  from  a  common  ancestor  must  remain  alike  dur- 
ing a  long  series  of  earlier  developmental  stages,  and  only 
in  later  stages  begin  to  diverge  from  one  another.  And 
this  is  just  what  the  centroepigenetic  hypothesis  implies, 
but  what  no  other  hypothesis  has  yet  been  able  to  explain. 

Further  the  hypothesis  of  centroepigenesis  teaches  us 
that  the  series  of  like  germinal  elements  must  be  shorter 
the  farther  removed  the  species  are  from  the  common 
ancestor.  Now  Morgan  as  is  well  known  has  obtained 
hybrids  in  which,  for  example,  eggs  from  Asteria  were 
fecundated  by  sperm  from  Arbacia,  which  belongs  to  the 
genus  Echinus.  The  two  parent  forms  belong  here  not 
only  to  two  different  genera  but  also  to  two  different 
classes.  But  these  hybrids  have  never  got  beyond  the 
larval  form,  the  pluteus  which  represents  only  one  of  the 
first  stages  of  ontogeny.68 

The  hypothesis  of  centroepigenesis,  finally,  regards 
development  as  completed  at  the  moment  when  all  the 
germinal  elements  have  achieved  activation.  We  note 
that  the  central  zone  is  then  no  longer  required  to  employ 
its  acquisitions  of  nutritive  material  for  the  growth  of  its 

*7Darwin:  Animals  and  Plants  under  Domestication.  II.  P.  13 — 
21 :  Crossing  as  a  direct  Cause  of  Reversion ;  P.  254. 

"Morgan:  Experimental  Studies  on  Echinoderm  Eggs.  Anat. 
Anzeiger,  Bd.  IX.  No.  5  and  6;  Dec.  23,  1893.  P.  151—152. 


IO2    Hypothesis  of  Structure  of  Germ  Substance 

entire  mass  or  for  the  restoration  of  the  masses  of  any  of 
its  specific  elements,  as  at  the  time  when  these  latter  were 
being  used  up  in  proportion  as  they  'became  activated. 
And  perhaps  this  explains  also  why  the  sex  cells,  which 
according  to  our  hypothesis  form  only  the  container  for 
the  germinal  substance  given  off  by  the  central  zone, 
usually  become  "ripe"  only  at  the  end  of  development. 

When  the  continuous  activation  of  new  specific  po- 
tential elements  ceases,  the  disturbing  influences  exercised 
by  the  central  zone  upon  the  dynamic  equilibrium  of  each 
ontogenetic  stage  will  cease  also.  And  thus  the  organism 
arrives  at  the  final  equilibrium  of  the  adult  condition. 
But  now  the  functional  stimulus  in  the  widest  sense  of  the 
term  can  come  into  play,  with  the  innumerable  variations 
possible  for  it,  as  new  causes  of  perturbation. 

So  just  as  formerly  the  perturbing  influence  of  the 
central  zone  upset  the  just  formed  equilibrium,  and  there- 
by provoked  a  transition  to  the  next  ontogenetic  stage, 
so  now  each  persisting  alteration  of  the  functional  stimu- 
lus disturbs  the  dynamic  equilibrium  of  the  adult  condi- 
tion and  thereby  causes  also  a  different  distribution  of  the 
general  nervous  energy.  Through  each  cell  of  the  entire 
organism,  or  of  definite  portions  of  the  organism,  there 
will  consequently  flow  a  nervous  current  specifically  dif- 
ferent, from  that  present  before,  and  also  specifically  dif- 
ferent from  one  cell  to  another. 

There  is  formed  and  deposited  therefore  in  the  nu- 
cleus of  each  of  these  cells  a  particular  specific  potential 
element,  which  will  add  itself  to  the  element  or  elements 
already  present.  But  all  the  elements,  the  new  as  well  as 
the  old,  which  are  deposited  in  the  somatic  nuclei  will  be 
lost  with  the  death  of  the  individual ;  and  only  those  will 
be  preserved  from  annihilation,  which  have  been  depos- 


How  New  Elements  Are  Deposited  103 

ited  in  the  nuclear  substance  of  the  central  zone.  The 
permanent  change  of  the  functional  stimulus  will  thus 
have  as  its  result, 'in  so  far  as  the  species  is  concerned, 
only  the  simple  addition  of  a  new  specific  potential  ele- 
ment to  the  germ  substance. 

We  must  therefore  now  study  in  what  way  this  new 
element  behaves  during  the  ontogenesis  of  the  succeeding 
organism.  But  this  investigation  will  form  the  object  of 
one  of  the  next  chapters. 

After  we  have  thus  brought  to  a  conclusion  this  short 
review  of  the  most  important  processes,  which  according 
to  our  view,  if  they  do  not  exactly  prove  the  centroepi- 
genetic  hypothesis,  yet  make  it  most  probable,  we  now  pass 
to  the  following  chapter,  which  will  afford  as  stated  still 
another  proof,  even  though  a  quite  indirect  one,  for  this 
hypothesis.  For  in  showing  that  while  a  whole  series  of 
facts  compels  us  to  reject  simple  epigenesis,  and  a  whole 
series  of  other  phenomena  compels  us  to  reject  pre forma- 
tion, it  will  make  it  seem  very  probable  that  a  hypothesis 
which  is  able  to  bring  both  series  of  phenomena  into 
accord  must  come  close  to  the  truth. 


CHAPTER  FOUR 

PHENOMENA  WHICH  REFUTE  SIMPLE  EPIGENESIS ;  AND 
PHENOMENA  WHICH  REFUTE  PREFORMATION.  INAD- 
MISSABILITY  OF  A  HOMOGENEOUS  GERM  SUBSTANCE; 
AND  INADMISSABILITY  OF  PREFORMISTIC  GERMS. 

I.     Phenomena  Which  Refute  Simple  Epigenesis 

Roux  designates,  with  the  expression  "self-differenti- 
ation" of  a  certain  part  of  the  organism,  the  process  in 
which,  according  to  a  certain  hypothesis,  "the  cause  of 
whatever  is  specific  in  the  differentiation  of  that  part  lies 
within  this  latter."  And  he  calls  "dependent  or  correla- 
tive differentiation"  the  opposite  process,  in  which,  ac- 
cording to  other  hypotheses,  whatever  is  specific  in  the 
alteration  which  goes  on  in  a  certain  part  of  the  organism 
during  development  is  determined  by  causes  lying  outside 
this  part.69 

If  an  ontogeny  consisted  only  of  self-differentiations, 
we  should  designate  the  development  as  evolutionary.  If 
on  the  contrary,  an  ontogeny  were  produced  only  through 
dependent  differentiations,  we  should  call  that  a  process 
of  epigenetic  nature. 

"Wilhelm  Roux:  Die  Methoden  zur  Hervorbringung  balber 
Froschembryonen  und  zum  Nachweis  der  Beziehung  der  erstcn 
Furchungsebene  des  Froscheies  zur  Medianebene  des  Embryo.  Anat. 
Anzeiger,  Bd.  IX.  February  1894,  P.  277 — 278.  Gesamm.  Abhandl., 
II,  P.  978. 

104 


Evolution  and  Epigenesis  105 

We  note  that  theoretically  a  mixed  or  intermediate 
hypothesis  would  be  conceivable,  according  to  which  a 
given  part  of  the  organism  would  be  differentiated 
through  the  cooperation  of  causes  lying  within  and  with- 
out it.  In  case  however  the  causes  lying  at  any  moment  of 
ontogeny  within  the  part  concerned,  do  not  arise  through 
any  antecedent  process  of  epigenetic  nature,  the  develop- 
ment at  least  up  to  this  time  must  be  considered  as  essen- 
tially purely  evolutionary.  But  if,  on  the  contrary,  the 
internal  causes  do  arise  through  an  antecedent  process  of 
epigenetic  nature  the  whole  development  would  then  be 
essentially  of  that  nature. 

Whitman  states  that  the  conception  of  modern  evo- 
lutionists differs  essentially  from  that  of  the  earlier  ovists 
and  spermatists ;  for  they  excluded  the  formation  of  new 
structural  parts  during  development,  a  thing  which  is  nat- 
urally admitted  by  the  evolutionists  of  to-day.  Accord- 
ing to  Mivart's  definition  which  Whitman  accepts  com- 
pletely, "the  term  evolution  may  be  employed,  as  it  has 
been,  to  denote  that  the  successive  formation  of  parts  pre- 
viously not  existent  is  due  not  to  their  imposition  from 
without  but  to  their  generation  from  within."  70 

According  to  this  definition  which  is  essentially  iden- 
tical with  that  of  Roux  above  cited,  evolution,  it  may 
here  be  repeated,  limits  to  a  minimum  the  influence  which 
the  various  other  parts  of  the  organism  exert  upon  the 
development  of  each  part,  or  considers  it  as  absolutely 
non-existent,  since  each  part  contains  within  itself,  or  in 
any  event  in  its  immediate  neighborhood,  the  causes  of  its 
progressive  development.  According  to  the  epigenetic 

70Whitman:  Evolution  and  Epigenesis.  Biol.  Lect.  at  the  Mar. 
Biol.  Lab.  of  Woods  Holl,  Summer  Session  1894.  Boston,  U.  S.  A., 
Ginu,  1896.  P.  224. 


io6        Phenomena  Refuting  Simple  Epigenesis 

hypothesis,  this  influence  is,  on  the  contrary,  of  the  very 
greatest  importance  and  is  considered  to  be  the  only 
cause  of  each  development. 

We  also  can  accept  Mivart's  definition  in  this  sense. 
We  note  that  it  does  not  include  in  any  way  the  con- 
ception of  preformistic  germs;  for  it  is  possible  that  the 
internal  causes  involved  arise  gradually  in  the  course  of 
development  and  need  not  be  already  present  in  the  germ 
substance.  In  the  first  case,  one  has  evolution  without 
preformistic  germs;  in  the  latter,  evolution  with  pre- 
formistic germs,  which  we  would  call  pre formation 
proper.  This  pre  formation  proper,  for  example  Weis- 
mann's  type,  is  also  included  in  the  definition  of  evolution 
just  given;  it  forms  however  only  a  special  case  of  it, 
which  is  limited  and  approximates  more  the  conception  of 
pre  formation  which  the  ovists  and  spermatists  enter- 
tained. 

The  processes  of  epigenetic  nature  can  be  regarded 
likewise  as  belonging  to  two  kinds,  corresponding  to  the 
above  mentioned  categories  of  evolution.  For  one  can 
conceive  of  processes  of  epigenetic  nature  both  with  pre- 
formistic germs  and  without  preformistic  germs,  and 
both  cases  are  actually  met  with. 

In  the  first  case  the  causes  which  bring  about  each 
specificity  of  development  would  be  already  present  in 
the  germinal  substance.  Only  their  liberation  or  acti- 
vation in  opportune  time  and  place  depends  upon  the 
reciprocal  action  of  the  different  parts  of  the  organism 
upon  one  another  (for  example  DeVries,  Oscar  Hertwig, 
etc.).  In  the  second,  on  the  contrary,  the  causes  pro- 
ducing the  different  specificities  of  development  arise  only 
gradually  in  the  course  of  ontogeny,  and  always  in  con- 


Theoretically  Conceivable  Kinds  of  Epigenesis  107 

sequence  of  the  reciprocal  action  of  the  different  parts 
of  the  organism  upon  one  another. 

We  will  call  the  first  of  these  processes  epigenesis 
with  preformistic  germs,  the  other,  epigenesis  without 
preformistic  germs,  or  epigenesis  proper. 

Further,  each  of  these  two  processes  can,  theoretically, 
be  divided  again  into  the  two  following  categories. 

One  can  conceive  of  the  reciprocal  action  of  the  dif- 
ferent parts  of  the  organism  upon  one  another,  as  such 
that  no  part  whatever  should  ever  be  considered  different 
in  any  way,  in  so  far  as  its  formative  action  on  the  other 
parts  is  concerned,  from  these  other  parts,  but  rather  all 
are  to  be  regarded  as  equally  necessary  and  of  equal 
value  in  this  respect.  Or,  on  the  other  hand  one  can 
suppose  that  among  all  the  parts  there  is  one  whose  action 
upon  the  other  parts  differs  through  some  peculiarity 
from  the  corresponding  action  of  all  other  parts,  so  that 
it  acquires  in  comparison  with  the  latter  much  greater 
importance. 

We  shall  designate  the  first  process  with  the  name 
"simple  epigenesis,"  or  briefly  "epigenesis,"  which  would 
be  equally  possible  either  with  or  without  preformistic 
germs,  and  we  shall  call  the  second  in  which  the  form- 
ative action  would  on  the  contrary  become  specially  local- 
ized in  a  definite  zone  of  the  organism,  by  the  name  of 
"localized  or  centralized  epigenesis,"  or  briefly  "centro- 
epigenesis."  Practically  it  would  be  conceivable  only 
without  preformistic  germs. 

Finally,  in  all  the  different  theories  without  pre- 
formistic germs,  one  could  conceive  of  the  germinal  sub- 
stance as  formed  of  a  single  homogeneous  substance  (or 
a  homogeneous  mixture  of  different  chemical  substances), 
or  of  a  material  which  though  not  consisting  of  pre- 


io8        Phenomena  Refuting  Simple  Epigenesis 

formistic  germs,  would  nevertheless  be  formed  of  a 
greater  or  less  number  of  specific  parts  different  from 
one  another. 

Of  all  these  hypotheses  which  one  can  form  concern- 
ing the  nature  of  the  developmental  process  and  the 
structure  of  the  germinal  substance,  we  need  discuss  here 
only  the  following  chief  ones,  and  consider  these  only 
very  briefly,  mentioning  the  others  only  casually  in 
passing.  We  arrange  them  in  the  following  way: 

Concerning  the  nature  of  the  developmental  process: 

1.  Simple    epigenesis    with    preformistic    germs    or 
without  such. 

2.  Evolution   with  preformistic   germs,    i.    e.,    pre- 
formation  proper. 

Concerning  the  structure  of  the  germinal  substance : 

1.  Germinal   substance  consisting  of   homogeneous 
material. 

2.  Germinal  substance  consisting  of  heterogeneous 
material.     Here  belongs  the  special  case  in  which  this 
substance  consists  of  preformistic  germs. 

We  can  now  pass  on  without  further  comment  to  a 
rapid  review  of  the  most  important  phenomena,  on 
account  of  which  simple  epigenesis  with  preformistic 
germs  or  without  such,  cannot  be  admitted.  This  will 
oblige  us  sometimes  to  return  to  the  phenomena  and 
arguments  with  which  we  were  occupied  in  the  preceding 
chapter. 

With  the  chief  facts  which  are  opposed  to  simple 
epigenesis  we  must  now  range  the  production,  already 
mentioned  and  discussed,  of  right  and  left,  anterior  and 
posterior,  half  embryos  of  frogs,  which  resulted  from 
the  killing  by  a  hot  needle  of  one  of  the  two  first 


Partial  Developments  109 

blastomeres.  As  is  well  known  it  was  these  very  half 
embryos  that  caused  Roux  to  construct  his  evolutionistic 
theory,  in  which  he  compares  development,  at  least  in 
so  far  as  the  four  quarters  of  the  embryo  come  into 
consideration,  with  a  mosaic  work. 

So  long  as  the  half  formations  arising  from  isolated 
blastomeres  are  limited  to  the  very  first  divisions,  so 
long  for  instance  as  one  of  the  first  two  blastomeres, 
when  isolated,  limits  itself  to  giving  half  of  the  total 
number  of  micromeres,  or  so  long  as  the  first  cleavage 
spheres  arising  from  the  isolated  blastomeres  succeed  each 
other  and  arrange  themselves  as  if  the  two  blastomeres 
had  remained  united,  so  long  there  is  still  nothing  to  be  seen 
in  these  phenomena  which  would  afford  any  proof  against 
simple  epigenesis.  For  in  general  we  can  suppose  that 
the  deutoplasm  alone  is  the  immediate  cause  of  the  num- 
ber, and  of  the  different  relative  sizes  and  disposition  of 
the  first  blastomeres.  If  then  the  relations  to  the  yolk 
of  the  blastomere  and  of  the  whole  of  the  blastomeric 
group,  could  not  by  themselves  constitute  any  proof 
change  through  the  isolation  of  the  blastomere,  it  is 
clear  that  the  first  cleavages  must  proceed  exactly  as 
though  no  isolation  whatever  had  taken  place. 

So  for  example  the  isolated  blastomeres  of  the  two 
or  four  cell  stage  of  the  egg  of  the  gastropod,  Ilyanassa 
obsoleta,  which  divide  in  essentially  the  same  manner  as 
they  would  if  they  were  part  of  the  complete  blastomeric 
group,  could  not  by  themselves  constitute  any  proof 
whatever  for  or  against  any  given  developmental  theory, 
so  long  as  the  separated  blastomeric  group  does  not  take 
on  any  really  specific  form.  For  in  this  Ilyanassa  obsoleta 
the  yolk  is  distinguished  by  its  great  mass,  thickness  and 


no        Phenomena  Refuting  Simple  Epiyenesis 

density.71  And  these  peculiarities  make  it  certain  that 
the  relation  of  the  isolated  blastomere  to  the  yolk  plasm 
is  not  different  from  that  which  would  have  existed  had 
it  remained  united  to  the  other  blastomere. 

But  the  preponderance  of  the  determinative  action  of 
the  yolk  is  limited  usually  to  the  early  stages  preceding 
the  gastrula.  It  has  no  influence  whatever  on  the  final 
form  of  the  embryo,  no  more  than  has  for  example,  the 
temporary  compression  of  the  blastomeres  between  two 
plates  or  the  shuffling  of  them.  Therefore  the  early 
cleavage  stages  have  no  specific  morphological  signi- 
ficance, as  is  evident  also  from  the  above  mentioned  fact, 
that  different  related  species  and  even  quite  widely 
separated  species  can  present  almost  identical  cleavage 
systems.72 

It  follows  from  this  that  as  soon  as  development 
commences  to  take  on  its  really  specific  form,  that  indi- 
cates that  the  action  of  the  germ  substance  is  preponder- 
ating over  the  action  of  the  yolkplasm  no  matter  in  what 
way  the  latter  may  formerly  have  acted. 

Consequently  simple  epigenesis  certainly  cannot  have 
recourse,  in  order  to  explain  the  half  embryos  of  Roux, 
to  the  fact  that  the  deutoplasm  remained  unchanged  in 
the  unsegmented  blastomere.  For  these  half  embryos 
arise  at  very  advanced  stages  of  development  and 
represent  quite  specific  formations. 

Nevertheless  Driesch  seems  to  want  to  explain  the 
half- formations  in  this  way:  "Each  particle  of  the  sur- 

71H.  E.  Crampton,  Jr. :  Experimental  Studies  on  Gasteropod  De- 
velopment. Arch.  1  Entwicklungsmech.  d.  Organismen.  Bd.  3; 
Heft.  i.  Leipzig,  Engelmann,  March  24,  1896. 

72Cf.  E.  B.  Wilson:  The  Cell-lineage  of  Nereis.  Journ.  of 
Morph.,  Vol.  VI,  No.  3.  Boston,  U.  S.  A.,  Ginn,  July  1892.  P.  455. 


Certain  Regenerations  ill 

viving  half  preserves  as  is  shown  by  Roux's  figures,  the 
position  which  it  would  have  had  in  normal  development. 
Then  after  segmentation  has  taken  place,  the  same  form- 
ative factors  act  on  each  particle  and  on  each  blastomere 
respectively,  which  would  have  acted  upon  them  in  nor- 
mal development,  consequently  also  the  same  forms  result ; 
Ergo :  half-embryo."  73 

From  the  epigenetic  standpoint  this  explanation  is 
inadmissible.  For  when  the  half  embryo  begins  to  take 
on  the  characteristic  form  of  its  species,  and  thereby 
indicates  as  we  have  seen  that  the  specific  action  of  the 
germ  substance  has  from  that  time  become  preponderant 
over  that  of  the  deutoplasm,  one  could  not  assert  that 
the  same  organ  forming  factors  continue  their  action,  for 
that  would  be  to  deny  that  there  is  any  formative  action 
at  all  exerted  by  the  idioplasmic  nuclear  substance  of  one 
entire  half,  left  or  right,  anterior  or  posterior,  upon  the 
other,  developing  half.  This  would  be  exactly  the  op- 
posite of  what  simple  epigenesis  postulates,  for  it 
attributes  the  tendency  of  development  to  take  on  its 
specific  form  of  equilibrium  to  the  reciprocal  action  of 
all  the  innumerable  little  masses  of  one  and  the  same 
idioplasm,  which  are  active  at  the  same  time  in  all  the 
nuclei  of  the  entire  organism. 

Roux  then  can  rightfully  assert  that  the  half  embryos 
constitute  by  themselves  the  most  direct  and  decisive 
refutation  of  the  theory  of  epigenesis. 

If  we  pass  on  now  from  half  embryos  to  the  regen- 
eration of  amputated  organs,  we  know  that  this  con- 
stitutes one  of  the  most  important  arguments  that  the 
epigenesists  ordinarily  advance  against  pre  formation. 

78Driesch :  Analytische  Theorie  der  organischen  Entwicklung. 
Leipiz,  Engelmann,  1894.  P.  15 — 16. 


112        Phenomena  Refuting  Simple  Epigenesis 

But  the  preformationists  on  their  side  cite  certain  partic- 
ular cases  of  regeneration  as  unfavorable  to  epigenesis: 
"Regeneration"  remarks  Roux,  "takes  place  in  tritons 
when  all  four  extremities  are  removed  at  one  time,  from 
which  it  follows  that  for  the  formation  of  new  extremities 
in  one  antimere,  the  presence  of  the  other  extremities 
is  not  in  the  least  necessary,  so  that  for  this  formation 
it  is  not  necessary  that  there  be  any  formative  correlating 
influence  extended  from  them."  74 

The  anachronisms  of  development  in  which,  for 
instance,  certain  parts  remain  behind  other  parts  in  their 
formation,  or  in  which  the  germ  layers  may  even  develop 
with  uneven  speed,  or  one  entire  half  of  the  body  may 
take  a  jump  ahead  of  the  other  half  so  that  one  can 
sometimes  observe  two  different  degrees  of  development 
in  the  two  halves  of  the  same  embryo,  belong  likewise 
to  the  number  of  phenomena  which  simple  epigenesis  is 
incapable  of  explaining:  "How  the  (epigenetic)  con- 
ceptions of  O.  Hertwig,"  Roux  writes  further, — and  his 
words,  already  quoted  above,  deserve  to  be  repeated  here, 
— "can  be  reconciled  with  these  anachronisms  in  the 
development  of  the  germ  layers  which  I  have  observed, 
or  indeed  with  the  absence  of  the  lower  layer — the  endo- 
blast  (Anentoblastia),  while  both  of  the  other  two  layers 
remain  essentially  normal  in  the  disposition  of  their 
parts,  or  finally  with  the  formation  of  half  embryos,  may 
well  be  left  to  the  reader's  own  judgment.  For  if  such 
large  parts  can  remain  behind  in  their  development,  or 
indeed  be  lacking  altogether,  and  the  other  parts  be  in 
no  wise  disturbed  thereby  in  their  development,  it  surely 
follows  that  the  development  of  these  latter  is  not  con- 

74Wilhelm  Roux:  Uber  Mosaikarbeit  etc.  Anat.  Hefte,  Febr. 
1893,  P.  299.  Gesamm.  Abhand.  II,  P.  839. 


Headless  but  Otherwise  Normal  Monsters      113 

nected  by  reciprocal  actions  with  the  absent  parts,  and 
therefore  is  not  carried  on  by  the  reciprocal  action  of 
all  the  parts  of  the  whole,  one  upon  another."  75 

It  is  the  same  with  headless  monsters  as  with  all 
monsters  which  lack  entire  parts  of  the  organism  but  are 
nevertheless  normal  in  the  other  parts.  Because  they 
show  likewise  that  there  does  not  exist  any  formative 
action  exercised  by  the  head,  or  by  other  parts,  upon 
the  rest  of  the  organism. 

While  thus  the  head  can  be  absent  in  development, 
the  presence  of  certain  other  parts  seems  on  the  con- 
trary to  be  indispensable  in  headless  omphalosite  mon- 
sters: "When  one  studies/'  writes  Dareste,  "headless, 
omphalosite  monsters  comparatively,  one  notes  that  the 
trunk  is  aknost  complete  in  some  cases  but  in  others 
incomplete.  And  upon  this  fact  is  based  Isadore  Geoffrey 
Saint  Hilaire's  division  of  headless  monsters  into  three 
different  types:  the  true  acephali,  in  which  the  thoracic 
region  is  as  well  developed  as  the  abdominal  region;  the 
paracephali,  which  have  only  the  abdominal  region;  and 
the  mylacephali  in  which  only  the  sacral  region  is  pres- 
ent. These  three  types  arise  through  inequalities  in  the 
development  of  the  cerebro-spinal  axis.  But  how  is  it 
that  the  posterior  part  of  this  axis  is  always  present, 
while  the  anterior  part  is  lacking  to  a  greater  or  less 
extent  ?  Why  does  not  the  reverse  appear  in  other  cases  ? 
This  depends  evidently  on  some  as  yet  unknown  fact 
of  embryogeny.  For  the  present  we  must  be  content 
with  the  mere  question."  76 

"Wilhelm  Roux:  Uber  Mosaikarbeit  etc.  Anat.  Hefte,  P.  320. 
Gesamm.  Abhandl.  II.  P.  859. 

"Dareste:  Recherches  sur  la  production  artificielle  des  mon- 
struosites.  Paris,  Reinwald,  1891.  P.  495. 


114        Phenomena  Refuting  Simple  Epiyenesis 

Nevertheless  some  other  varieties  of  omphalosite 
monsters  seem  to  show  that  the  presence  of  any  part 
whatever  of  the  vertebral  axis  is  sufficient  to  permit 
at  least  partial  development;  for  instance  in  the  cephalic 
monsters  the  embryo  consists  generally  of  the  head 
alone.77  We  note  however  that  these  monsters  com- 
monly contain  the  anterior  extremity  of  the  spinal  cord 
which  can  have  been  only  slightly  differentiated  in  the 
embryonic  stage  at  which  the  incomplete  development  is 
arrested.  In  some  of  these  cephalic  omphalosite  mon- 
sters, a  large  part  of  this  anterior  extremity  of  the  spinal 
cord  may  even  have  undergone  a  process  of  reabsorption 
after  the  previous  arrest  of  the  partial  development. 

As  we  shall  see  soon  Born  succeeded  in  producing 
artificially  a  thing  like  these  cephalic  omaphalosite  mon- 
sters by  grafting  upon  a  complete  tadpole  a  piece  removed 
from  another  tadpole,  and  consisting  only  of  the  head 
and  a  small  part  of  the  elongated  medulla. 

Concerning  the  double  monsters  with  double  sym- 
metry, it  will  be  worth  while  to  repeat  once  more  in 
extenso  the  following  statement  of  Roux,  even  though 
we  have  reported  it  already,  for  the  most  part,  in  the 
preceding  chapter: 

"This  additional  fact  speaks  directly  against  the 
achievement  of  development  of  the  individual  through 
a  general,  reciprocal,  formative  cooperation  of  all  parts 
to  form  a  whole;  namely  that  in  the  chief  class  of  double 
monsters,  and  so  in  those  double  formations  which  cor- 
respond to  the  law  which  I  formulated  of  the  double 
symmetry  of  the  anlagen  of  organs,  the  piece  absent 
in  a  symmetrically  similar  way  from  each  of  the  two 

"Dareste :  Recherches  sur  la  prod,  artif.  des  monstr.     P.  498. 


Connected  Partial  Embryos  of  Roux  115 

individuals  may  actually  be  any  given  piece  whatever 
that  is  limited  by  a  plane  surface;  and  that  in  them  the 
organs  are  nearly  all  present  in  their  normal  form  up 
to  the  plane  of  reunion,  just  as  if  two  symmetrical  pieces 
had  been  cut  away  so  as  to  leave  two  plane  surfaces, 
from  two  twins,  after  they  were  fully  developed  and 
ready  for  birth,  and  the  foetuses  had  then  been  united 
by  the  cut  surfaces.  This  normal  formation  of  defective 
organs  up  to  any  given  plane  of  separation  as,  for 
example,  the  8-shaped  double  cornea  or  double  lens  of 
the  third  eye  common  to  both  organisms,  speaks  likewise 
strongly  in  favor  of  a  capacity  of  self-differentiation 
possessed  even  by  parts  of  these  organs,  as  the  simul- 
taneous development  of  two  structures  united  so  exten- 
sively, to  form  bodies  of  which  each  is  self  centered, 
indicates  directly  the  absence  of  the  action  of  general 
reciprocal  influences,  connecting  them  into  one  whole/' 78 
We  remark  nevertheless  in  our  turn  that  the  evolu- 
tionistic  theory  does  not  in  any  way  explain  as  Roux 
asserts,  how  the  two  organisms  are  limited  by  a  plane 
surface  which  is  perfectly  symmetrical,  rather  than  by 
any  kind  of  irregular  surface  whatever.  This  theory 
merely  shows  that  it  is  possible  that  the  development  of 
organs  which  differentiate  themselves  automatically,  may 
be  arrested  at  any  given  surface,  without  thereby  dis- 
turbing the  normal  form  of  any  of  the  remaining  portions, 
not  even  in  the  neighborhood  of  the  surface  where 
development  is  arrested.  But  it  does  not  explain  why 
the  surface  of  division  must  be  a  plane  surface,  and 
perfectly  symmetrical  in  the  two  individuals.  One 
should  rather  expect  here  a  manifold  reciprocal  inter- 

"Wilhelm  Roux:  Uber  Mosaikarbeit  etc.    Anat.  Hefte,  P.  320. 
Gesamm.  Abhandl.   II.    P.  859—860. 


Ii6        Phenomena  Refuting  Simple  Epigenesis 

locking  of  the  two  organisms  which  would  give  a  most 
asymmetrical  and  irregular  dividing  surface. 

The  continuation  of  development  in  the  tail  frag- 
ment of  the  tadpole  seems  to  speak  likewise  against  both 
epigenesis  and  pre formation.  For  in  his  experiments 
upon  tadpoles,  Born  has  proven  the  accuracy  of  Vulpian's 
statement  that  the  amputated  tails  not  only  continue  to 
live  for  sometime  (some  even  thirteen  days),  but  con- 
tinue to  grow  and  to  differentiate  into  their  various 
tissues.  He  has  further  observed  the  following  processes 
of  new  formation. 

"A  few  days  after  the  amputation,  the  margins  of 
the  fin  of  the  amputated  tail  commence  to  grow  over  the 
cut  surface  of  the  axis ;  they  unite  in  front  of  it  to  form 
a  high  semicircular  tail  fin.  The  axis  is  not  entirely 
without  participation  in  this  process,  for  prolongations 
of  the  notochord  as  well  as  of  the  spinal  cord  grow 
into  the  newly  formed  fin,  but  the  metameric  muscu- 
lature showrs  nothing  like  this  and  terminates  sharply  at 
the  original  surface  of  amputation.  But  this  prolonga- 
tion of  the  notochord,  like  that  of  the  spinal  cord,  even 
in  the  most  favorable  instances,  scarcely  extends  half  as 
far  forward  in  front  of  the  cut  end  of  the  original  axis 
as  does  the  newly  formed  marginal  fin.  This  latter  is 
formed  of  typical  embryonic  mucous  connective  tissue 
with  a  few  pigment  cells  scattered  through  it.  I  have 
not  been  able  to  discover  in  it  any  rudiments  of  vessels." 

"This  observation  teaches  then,"  continues  Born, 
"that  the  provision  of  yolk  in  the  tail  end  cut  off  from 
a  tadpole  does  not  serve  merely,  as  Vulpian  has  already 
shown,  for  further  growth,  and  further  differentiation 
of  the  tissues,  and  for  the  formation  of  a  new  structure 
growing  out  from  the  cut  surface,  but  it  shows  that 


Growth  of  Amputated  Parts  and  Grafts       117 


besides  the  fin  margin,  the  notochord  and  the  spinal  cord 
take  part  in  this  new  formation.  It  is  interesting  that 
the  tail  of  a  tadpole  is  capable  of  such  a  regenerative 
new  formation  not  only  in  the  caudal  direction  but  also 
in  the  opposite  direction."  79 

We  say  then  that  these  phenomena,  which  the  ampu- 
tated tail  of  the  tadpole  presents,  can  be  cited  by  the  pre- 
formationists  against  the  epigenesists,  as  well  as  by  the 
latter  against  the  former.  For  the  former  can  object 
that  the  progress  of  the  histological  differentiation  in 
the  fragment  of  tail  cut  off  from  all  the  rest  of  the 
organism  would  denote  the  absence  of  any  action  of 
the  organism  upon  the  development  of  this  part  of  the 
body,  and  the  epigenesists  on  their  side  could  show  that 
the  power  of  the  tail  to  regenerate  even  in  the  direction 
from  the  tail  toward  the  head,  could  not  be  explained 
by  preformation,  even  with  the  aid  of  reserve  idioplasm, 
for  that  could  effect  regeneration  only  in  the  direction 
from  the  head  toward  the  tail. 

It  is  the  same  with  Bern's  celebrated  experiments  on 
the  grafting  of  certain  fragments  of  tadpoles  upon  one 
another  or  upon  complete  tadpoles,  which  are  opposed 
to  simple  epigenesis  and  at  the  same  time  indicate  a 
process  of  epigenetic  nature. 

In  the  first  place  they  are  opposed  to  epigenesis.  For 
in  all  grafts  of  parts  of  tadpoles  upon  complete  tadpoles, 
the  grafted  parts  have  continued  their  development  regu- 
larly as  if  they  had  remained  united  to  their  own 
organisms.  Therefore  the  rest  of  this  organism  has  not 
under  normal  conditions  any  influence  upon  the 
development  of  these  portions. 

"Born:  Uber  Verwachsungsversuche  mit  Amphibienlarven. 
Leipzig,  Engelmann,  1897.  P.  32—33. 


n8        Phenomena  Refuting  Simple  Epigenesis 

Thus  for  example  a  larva  of  Rana  esculenta  from 
which  there  had  been  cut  off  the  most  anterior  part  of 
the  head  including  the  eye  anlagen,  the  anterior  part 
of  the  brain,  the  nasal  groove,  and  the  primitive  mouth, 
was  so  grafted  upon  the  caudal  half  of  the  abdomen  of 
a  complete  larva,  as  to  form  an  acute  angle  between  the 
back  of  the  former  and  the  abdomen  of  the  latter,  the 
abdomen  of  the  former  being  turned  toward  the  head 
of  the  latter.  After  allowing  the  double  larva  twelve 
days  of  development,  it  was  killed  and  it  showed  that 
"all  the  organs  of  the  partial  larva  up  to  the  surface  of 
amputation  and  union  had  developed  quite  as  com- 
pletely as  though  there  was  no  part  of  them  lacking 
and  as  though  their  normal  environment  and  their  or- 
dinary relations  were  quite  undisturbed."  80 

The  anterior  portion  of  a  larva  so  short  that  it 
scarcely  extended  beyond  the  commencement  of  the  elon- 
gated spinal  cord,  was  grafted  upon  the  abdomen  of  a 
complete  larva,  and  continued  to  develop  normally. 
"All  parts  developed  completely  up  to  the  surface  of 
amputation:  the  cartilaginous  trabeculae,  the  quadrates 
with  the  chewing  muscles  covering  them,  behind  the 
mouth  cavity  the  cartilages  of  Meckel,  the  cartilages  of 
the  lower  jaw  and  behind  these  again  the  hyoids." 81 

Upon  these  and  other  similar  examples,  Born  bases 
the  following  conclusions :  "Although  up  to  the  moment 
of  grafting  there  had  been  no  trace  (of  primordial  cra- 
nium) present,  and  the  mesoderm  from  which  it  develops 
remained  in  a  quite  indifferent  and  almost  primitive  con- 

80Born:     Uber     Verwachsungsversuche     mit     Amphibienlarven. 

P.  97- 

81Born:  Uber  Verwachsungsversuche  mit  Amphibienlarven. 
P.  108—109. 


Nuclear  Somatization  119 

dition,  nevertheless  the  complicated  and  characteristic 
parts  of  the  head  were  developed  up  to  the  surface  of 
amputation  completely  and  in  their  perfect  form,  and 
not  only  entire  structure  but  also  parts  of  these  structures." 

"Whatever  development  there  is  going  on  beyond 
the  stage  at  which  amputation  was  performed  depends 
essentially  on  self-differentiation  of  the  individual  parts; 
no  correlative  influence  of  the  neighboring  parts  or  of 
the  entire  organism  can  ever  be  recognized,  either  nega- 
tively or  positively.  Thus  this  development  beyond  the 
stage  at  which  amputation  was  performed,  corresponds 
entirely  with  Roux's  mosaic  theory."  82 

Nevertheless,  we  shall  see  soon  that  another  whole 
series  of  Bern's  experiments,  as  also  those  just  recorded 
if  one  considers  them  from  another  point  of  view,  are 
no  less  opposed  to  evolutionary  hypotheses  in  general 
and  to  hypotheses  of  pre formation  properly  so  called  in 
particular. 

In  short,  the  observations  and  experiments  which  we 
have  thus  far  cited,  from  the  half-embryos  of  Roux  to 
the  tadpole  fragments  of  Born,  all  show  the  possibility 
that  individual  parts  of  the  organism,  provided  they  con- 
tain any  part  whatever  of  the  vertebral  axis,  can  develop 
independently  of  the  remaining  parts,  and  are  sufficient 
by  themselves  alone  to  prove  the  inadmissibility  of  simple 
epigenesis. 

But  the  preformists  had  yet  another  fundamental 
objection  to  make  to  the  epigenesists,  who  have  sought 
so  far  in  vain  for  a  reply  to  it :  namely  that  epigenesis 
requires  the  renunciation  of  nuclear  somatization.  For 
these  two  hypotheses  are  absolutely  irreconcilable.  It 

82Born:  Uber  Vcrwachsungsversuche  mit  Amphibienlarven. 
P.  204—205. 


I2O        Phenomena  Refuting  Simple  Epigenesis 

follows  therefore  that  each  fact  or  each  argument  which 
speaks  in  favor  of  nuclear  somatization,  is  at  the  same 
time  a  proof  against  epigenesis.  And  we  saw  precisely 
in  the  preceding  chapter,  that  there  is  a  whole  series  of 
facts  and  arguments,  which  it  would  be  useless  to  repeat 
here,  but  which  compel  us  to  admit  this  nuclear 
somatization  as  an  incontrovertible  fact. 

The  preformationists  can  finally  object  to  epigenesis 
and  not  unreasonably,  that  by  its  "attainment  of  equilib- 
rium," it  does  not  explain  the  termination  of  ontogeny 
as  well  as  preformation  does.  For  why  should  the 
reciprocal  actions  of  all  parts,  on  which  development 
depended  up  to  that  time,  suddenly  cease  to  effect  any 
further  change  when  once  the  adult  stage  is  reached? 
Because  it  is  only  then,  reply  the  epigenesists,  that  the 
dynamic  equilibrium  is  attained.  But  if  the  successive 
ontogenetic  forms  repeat  the  phylogenetic,  how  comes 
it  that  the  dynamic  equilibrium  which  once  existed  in 
each  of  these  latter  does  not  remain  existent  in  any  of 
the  former?  And  if  the  absence  of  equilibrium  at  all 
these  stages  is  due  to  some  alteration  of  the  formative 
living  substance,  how  then  could  this  new  substance  pass 
again  during  a  long  series  of  stages  through  the  same 
phylogenetic  ancestral  forms?  The  preformists,  on  the 
contrary,  have  no  trouble  in  explaining  the  arrest  of 
development  since  according  to  their  theory  it  would 
follow  only  at  the  moment  when  there  would  be  present 
in  each  cell  only  a  single  kind  of  preformistic  or 
determinant  germs. 

Having  thus  made  a  rapid  review  of  the  principal 
objections  which  compel  us  to  reject  epigenesis,  we  can 
pass  on  to  an  equally  brief  consideration  of  a  number 


Complexity  of  Prefonnistic  Germ  Plasm         121 

of   objections    which    stand    in    the    way    of    admitting 
preformation. 

2.     Facts  Which  Compel  the  Rejection  of  Preformation 

If,  limiting  ourselves  to  the  most  typical  theory  of 
preformation  to  which  all  the  others  can  be  finally 
reduced,  we  consider  that  of  Weismann,  we  encounter 
at  the  outset  a  very  simple  argument  which  is  yet  so 
formidable  that  it  is  in  itself  enough  to  discourage  the 
most  firmly  convinced  partisan  of  that  doctrine. 

For  the  preformation  theory  of  Weismann  forces 
him  to  suppose  for  the  infinitely  numerous  particles 
constituting  the  different  determinants  or  groups  of 
determinants,  an  excessively  complicated  architecture  or 
excessively  complicated  arbitrary  mode  of  disposition. 
Now  the  elementary  fact  of  reproduction  demonstrates 
that  the  constitution  of  the  germ  plasm,  whatever  it 
may  be,  does  not  become  at  all  altered  when  this  latter 
divides  and  distributes  itself  among  the  incalculable 
number  of  germ  cells  which  can  be  produced  by  each 
organism  and  by  all  its  succeeding  generations.  Weis- 
mann must  first  then  explain  to  us  how  the  subdivision  of 
a  given  germ  plasm  into  new  parts  in  each  of  which  this 
very  complicated  structure  is  preserved  uninjured  or 
is  accurately  reproduced  again,  is  possible.  That  is 
fundamentally  the  same  difficulty  which  the  old  ovists 
and  spermatists  encountered,  and  which  they  endeavored 
to  overcome  by  their  idea  of  the  encasement  of  the 
germs.83 

Weismann  has  since  endeavored  to  weaken  the  force 

83Among  others  compare  e.  g.  Oscar  Hertwig:  Praformation 
oder  Epigenese?  P.  u. 


122   Facts  Compelling  Us  to  Reject  Pre formation 

of  this  objection  by  taking  into  consideration,  besides 
the  architecture  of  the  germ  plasm  itself,  also  the  uneven 
rapidity  of  multiplication  of  the  different  determinants 
and  the  reciprocal  forces  of  attraction  exercised  by  these 
latter  upon  one  another,  as  factors  which  determine  the 
orderly  division  of  each  plasm  or  each  id.84  But,  as 
this  author  himself  admits,  the  architecture  of  the  germ 
plasm  remains  necessarily  the  principal  factor,  and  conse- 
quently the  objection  of  the  incompatibility  of  this  arbi- 
trary architecture  with  constant  complete  division  of  the 
plasm  without  alteration,  remains  in  all  its  force. 

Another  argument  which  presents  itself  likewise 
against  pre formation  is,  that  with  the  exception  of  the 
partial  developments  cited  in  the  preceding  section  of 
parts  which  each  contained  one  very  definite  zone  of  the 
organism,  it  has  never  been  possible  to  obtain  the  devel- 
opment or  the  continuation  of  development  of  somatic 
parts,  even  though  they  are  capable  of  living  for  some 
time  after  they  have  been  detached  from  the  rest  of  the 
organism. 

One  would  certainly  not  regard  as  a  continuation  of 
normal  development  the  mere  increase  in  mass  which 
takes  place  in  parts  cut  off  from  the  fetal  organism, 
when  they  are  transplanted  upon  tissues  which  on  account 
of  their  great  richness  in  blood  vessels  are  especially 
capable  of  affording  abundant  nourishment  to  their  new 
guests. 

This  simple  increase  in  mass  depends  for  the  most 
part  on  an  actual  multiplication  of  the  respective  cells, 
which  proceeds  in  directions  determined  either  by  nutri- 
tion alone  or  by  the  path  of  least  resistance  in  the  environ- 

"Weismann:  Das  Keimplasma.  Eine  Theorie  der  Vererbung. 
Jena,  Fischer,  1892.  P.  86. 


Transplanted  Parts  Soon  Cease  to  Develop     123 

ment,  accompanied  either  by  no  morphologic  alterations 
or  by  quite  aspecific  ones,  depending  upon  whether  the 
portion  cut  away  consisted  of  a  formless  fragment  of 
tissue,  or  of  an  organ  whose  proper  form  was  already 
indicated.  We  may  mention,  for  example,  Zahn's  trans- 
plantations of  portions  of  cartilaginous  or  bony  fetal 
tissues  to  the  lungs  and  kidneys  of  other  individuals  of 
the  same  or  different  species,85  or  Fischer's  transplanta- 
tions of  anterior  and  posterior  extremities  of  chicken 
embryos  (especially  of  one  incubated  only  eleven  days) 
to  the  comb  or  ruff  of  the  cock.86 

It  is  true  that  both,  and  especially  Fischer,  have 
observed  that  in  these  extremities  of  chicken  embryos, 
ossification,  which  at  the  time  of  amputation  had  not 
commenced  at  all  or  had  scarcely  commenced,  was 
initiated  or  continued  in  the  transplanted  extremities.87 
But  this  process  of  ossification  can  be  considered  only 
as  the  mere  accumulation,  and  consequent  intensification, 
of  the  effects  of  the  specific  vital  activity  which  was 
already  at  work  before  the  amputation,  and  which 
persists  unaltered  after  the  transplantation. 

Consequently  we  think  that  Roux  is  quite  wrong 
when,  apropos  of  these  experiments  of  Zahn,  Fischer, 
and  others,  he  expresses  himself  as  follows:  "These 
experiments  have  demonstrated  that  many  isolated 
embryonic  parts  can  not  only  grow  but  even  become 

"Zahn :  Uber  das  Schicksal  der  in  den  Organismus  implantierten 
Gewebe.  Virchows  Archiv,  Bd.  95.  Drittes  Heft,  5.  March  1884; 
especially  e.  g.  P.  374—375,  380,  381. 

"Fischer:  Uber  Transplantationen  von  organischem  Material. 
Deutsche  Zeitschrift  der  Chirurgie,  Bd.  17.  Erstes,  Zw.,  Dr.  u.  Viertes 
Heft,  1882;  especially  e.  g.  P.  362 — 363,  370 — 371. 

87E.  g.  Zahn:  Uber  das  Schicksal  etc.  P.  382ff.— Fischer :  Uber 
Transplantationen  etc.  P.  370,  374. 


124  Facts  Compelling   Us  to  Reject  Pre formation 

histologically  differentiated  in  an  approximately  normal 
way.  It  follows  that  the  differentiation  of  these  parts 
is  not  a  function  of  reciprocal  actions  between  these 
parts  and  other  parts.  Therefore  there  is  thus  already 
proven  a  certain  histologic  and  morphologic  self-differ- 
entiation of  many  parts  of  the  developing  egg."  88 

This  is  not  correct.  For  these  experiments  show, 
we  repeat,  only  a  mere  increase  in  mass  of  these  tissues, 
which  is  morphologically  without  any  specific  character; 
and  the  continuation  of  the  histologic  differentiation 
which  had  already  commenced  or  was  on  the  point  of 
commencing  at  the  moment  of  amputation,  is  explicable 
by  the  simple  accumulation  of  the  effects  of  the  same 
vital  process  which  merely  persists  exactly  as  it  was 
before  the  amputation. 

Another  argument  against  pre formation  is  the  great 
capacity  of  modification  of  the  organism  while  it  is 
undergoing  development,  as  well  as  when  fully  developed, 
to  which  it  owes  its  remarkable  power  of  adapting  itself 
to  quite  abnormal  conditions.  For  the  preformation 
theory  with  its  determinants,  which  are  bound  up  with 
one  another  into  a  solid  structure,  and  of  which  each 
determines  the  formation  even  of  the  smallest  particles 
and  their  most  minute  variations,  implies  undeniably  a 
great  morphological  rigidity,  which  is  not  reconcilable 
with  the  great  mutability  of  the  organism. 

"Galls,"  says  Oscar  Hertwig,  for  example,  "are 
valuable  witnesses  against  the  germ  theory  of  Weismann. 
They  teach  us  that  cells  of  plant  bodies  can  serve  quite 
other  purposes  than  could  have  been  foreseen  during 

"Wilhelm  Roux :  Zur  Orientierung  iiber  einige  Probleme  der 
embryonalen  Entwicklung.  Zeitschrift  fur  Biologic;  Bd.  XXI.  July 
1885.  P.  480—482.  Gesammelte  Abhandlungen.  II,  P.  206—207. 


Adaptability  and  Alterability  of  Structures     125 


development,  that  they  can  adapt  their  form  to  new 
conditions,  and  that  their  specific  form  is  not  determined 
by  special  determinants  in  the  nucleus  but  by  external 
stimuli."  89 

The  stomach  of  the  tern,  which  ordinarily  feeds 
on  fish,  is  lined  by  a  soft  mucous  membrane.  If 
one  feeds  it  with  wheat  for  a  few  weeks  its  stomach 
develops  a  superficial  horny  coat,  its  musculature  is 
strengthened  and  it  takes  on  the  character  of  a  gizzard.90 
If  these  stomachs  belonged  to  two  varieties  of  the  same 
species,  Weisinann  would  have  no  hesitation  in  attribut- 
ing the  diversity  to  special,  and  thus  different,  determi- 
nants which,  as  the  facts  show,  do  not  really  exist. 

Loeb  has  demonstrated  that  the  colored  design  of 
the  yolk  sac  of  a  fish  embryo  (Fundulus)  is  not  in  itself 
predetermined,  but  depends  upon  the  distribution  of 
blood  vessels.  The  pigment  cells  are  at  first  distributed 
uniformly  but  when  the  circulation  of  the  yolk  sac  is 
established,  they  migrate  toward  the  vessels,  attracted 
probably,  as  Loeb  supposes,  by  a  chemical  substance  in 
the  blood,  and  give  rise  thus  to  a  definite  design.  Graf 
has  likewise  recently  demonstrated  that  the  color  designs 
of  the  leech  are  not  themselves  inherited,  but  that  they 
depend  upon  the  disposition  of  muscle  fibers  in  which 
the  amoeboid  pigment  cells  lie.  It  would  be  absurd, 
•concludes  Wilson,  to  imagine  in  all  of  these  cases  a 
special  series  of  determinants  for  each  individual  color 
design.91 

890scar  Hertwig:  Zeit-  und  Streitfragen  der  Biologic.  I.  Pra- 
formation  oder  Epigenese?  P.  48 — 49. 

80Delage:    L'heredite  etc.     P.  604. 

91E.  B.  Wilson :  The  embryological  Criterion  of  Homology.  Biol. 
Lect.  at  the  Mar.  Biol.  Lab.  of  Wood's  Holl ;  Summer  Session  1894. 
Boston,  U.  S.  A.,  Ginn.  1896.  P.  116. 


126    Facts  Compelling  Us  to  Reject  Pre formation 

Everybody  knows  the  peculiar  static  structure  of  bone. 
Substance  becomes  accumulated  in  bone  at  the  points  of 
greatest  pressure,  and  attains  thus  its  best  possible  utiliza- 
tion. Now  it  is  known,  as  J.  Wolff  discovered  and  as 
Kastor,  Martiny  and  J.  Rabe  have  confirmed,  that  similar 
structures  are  formed  also  in  quite  new  and  abnormal 
circumstances  in  connection  with  new  static  conditions, 
for  example,  in  bones  broken  and  reset  at  an  angle. 
"From  this  it  follows,"  says  Roux,  "that  these  forma- 
tions do  not  need  to  be  fixed  and  inherited,  but  arise  of 
themselves  whenever  the  conditions  exist.  As  the  static 
structure  of  bones  is  developed  in  a  clearly  recognizable 
form  only  after  the  first  years  of  life,  one  can  not  say 
anything  of  the  necessarily  hereditary  transmission  of 
it,  without  special  researches  upon  this  point." 92 

Teratogenesis  in  general,  both  natural  and  artificial, 
is  quite  opposed  to  preformation.  It  denotes  that  the 
organism,  at  any  rate  while  it  is  still  in  process  of  devel- 
opment, can  adapt  itself  to  exceptional  conditions  which 
are  quite  different  from  the  normal.  And  it  accom- 
plishes this  by  producing  abnormal  formations  whose 
development  must  consequently  be  due  only  to  a  process 
of  epigenetic  nature,  and  cannot  be  of  preformistic 
nature. 

Let  us  consider  one  of  the  simplest  examples.  In 
the  hemiteratic  spina  bifida,  the  spinal  opening  is  ordi- 
narily covered  over  by  a  layer  consisting  of  fibrous 
tissue  like  that  of  scars,  which  in  some  cases  takes  on 
all  the  characters  of  the  skin.  Then  the  spinal  opening 
is  not  visible  from  the  outside.  But  when  the  spinal 
opening  is  in  the  lumbar  region  it  is  not  rare  for  a 

*2Roux :  Der  Kainpf  der  Teile  im  Organismus.   P.  28. 


Adaptability  Irreconcilable  with  Pre formation      127 

considerably  developed  tuft  of  hair  to  appear  on  the 
outside.93  Would  Weismann  also  presuppose  its  own 
determinants  for  this  tuft?  And  if  this  tuft  arises 
without  being  represented  in  the  germ  plasm  by  its  own 
determinants,  why  cannot  the  same  process  occur  in 
normal  development  for  other  parts  of  the  organism? 
Normal  and  abnormal  development  do  not  differ  essen- 
tially from  each  other;  and  the  causes  which  produce 
them  are  of  the  same  nature  in  both. 

Weismann  certainly  recognized  the  great  importance 
of  the  capacity  of  alteration  by  functional  adaptation, 
possessed  by  both  embryonic  and  adult  organisms.  "If 
this  principle  did  not  exist,"  he  writes,  "the  organism 
would  be  like  a  building,  of  which  each  stone  is  already 
prepared  before  the  situation  and  use  of  the  building  is 
determined.  Such  a  predetermined  ontogenesis  could 
not  produce  any  organism  capable  of  living.  The  influ- 
ences under  which  organisms  exist  during  their  develop- 
ment are  never  exactly  the  same  and  to  be  able  to 
adapt  themselves  to  them  they  must  possess  a  certain 
freedom."  94 

But  we  cannot  repeat  often  enough,  that  this  great 
capacity  of  adaptation  is  absolutely  irreconcilable  with 
his  theory  of  determinants,  or  with  any  preformistic 
composition  of  the  germ  substance.  If  functional  adapta- 
tion effects  "the  adjustment  of  the  primary  hereditary 
anlagen,  that  is  of  the  determinants,  to  new  circum- 
stances," 95  this  signifies  that  these  new  circumstances 

88Dareste:  Recherches  sur  la  production  artificielle  des  mon- 
struosites.  P.  327,  538. 

"Weismann :  The  Effect  of  External  Influences  upon  Develop- 
ment. The  Romanes  Lectures,  1894.  P.  16 — 17. 

"Weismann:  Ibid,  P.  16. 


128    Facts  Compelling  Us  to  Reject  Pre formation 

external  or  internal  to  the  individual  exert  upon  these 
determinants  a  certain  formative  action.  But  if  one 
assumes  that  a  certain  formative  action  becomes  thus 
exerted  upon  each  of  the  determinants  by  abnormal  cir- 
cumstances in  their  development,  one  must  then  assume 
that  a  similar  formative  action  is  exerted  upon  each  of 
these  same  determinants  by  the  other  parts  of  the  organ- 
ism when  the  development  of  these  parts  proceeds  quite 
normally.  But  what  remains  then  of  the  preformistic 
action  of  these  determinants  which  should  fashion  the 
organism  like  a  piece  of  mosaic-work? 

The  experiments  of  Born  also,  which,  as  we  have 
seen  above,  are  absolutely  opposed  to  simple  epigenesis 
are  just  as  little  reconcilable  with  preformation,  because 
they  denote  in  general  the  epigenetic  nature  of  the  process 
of  growth.  We  need  recall  here  only  the  union  of 
portions  of  different  tadpoles ;  for  example,  of  the  anterior 
portion  of  one  tadpole  with  the  posterior  portion  of 
another. 

In  this  latter  case,  if  the  anterior  portion  were  limited 
by  a  section  passing  through  the  medulla  oblongata,  while 
the  posterior  portion  had  been  obtained  by  a  section 
passing  through  the  medulla  spinalis,  it  would  follow 
that  the  two  surfaces  of  amputation  of  the  medulla 
which  ought  to  match  exactly  would  present  on  the  con- 
trary unlike  forms  and  surfaces.  In  spite  of  this  a 
short  time  after  the  two  ends  of  the  medulla  were  united, 
the  two  half  tadpoles  having  meanwhile  continued  their 
development,  they  showed  a  union  in  which  no  angle 
or  sharp  fault  persisted  but  gentle  curves  of  transition 
were  present  instead.  The  two  medullary  canals  went 
over  into  one  another  also  gradually  and  without  inter- 
ruption, so  that  one  could  no  longer  recognize  the  exact 


Secondary  C captation  in  Grafts  129 

point  of  their  union.  "This  is  an  example  of  the  phe- 
nomenon observed  also  in  all  the  other  organs,  that 
after  the  growing  together  of  two  sections  of  unequal 
size  and  form,  the  uneven  character  of  the  union,  present 
at  first,  disappears  and  gradually  a  smooth  connection 
of  the  surfaces  is  established."  96 

The  union  of  the  corresponding  organs  of  the  two 
fragments  is  quite  intimate:  for  example  in  the  case 
which  we  have  just  cited,  longitudinal  sections  of  the 
two  united  medullas  showed  that  the  fibers  of  the  white 
substance  of  the  medulla  spinalis  went  over  continuously 
into  those  of  the  white  substance  of  the  elongated  medulla 
oblongata.97 

Among  the  experiments  of  Born,  those  upon  the 
artificial  production  of  double  monsters  are  especially 
remarkable.  They  were  obtained  by  joining  two  tadpoles 
together  in  the  most  diverse  ways.  In  the  case  which 
we  now  report  he  cut  away  from  each  of  two  tadpoles 
the  upper  part  of  the  ventricles  of  the  brain  and  joined 
the  two  cut  surfaces  together  so  that  both  the  tails  and 
the  bellies  of  the  two  tadpoles  constituting  the  double 
monster  were  directed  in  opposite  ways.  Here  also,  there 
took  place,  in  so  far  as  the  two  tadpoles  developed,  a 
complete  union  so  that  after  sometime  there  could  not 
be  perceived  any  transition  stage  between  the  surfaces  of 
the  corresponding  organs  which  were  united  together. 

"It  is  impossible  to  believe,"  remarks  Born  in  this 
connection,  "that  in  placing  these  two  tadpoles  one  upon 
the  other,  the  small  ventricular  clefts  and  the  external 
walls  of  the  two  brains  could  be  applied  exactly  one  upon 

*'G.  Born :  Uber  Verwachsungsversuche  mil  Amphibienlarven. 
P.  53—54- 

B7G.  Born:  Uber  Verwachsungsversuche  usw.  P.  56. 


130  Facts  Compelling  Us  to  Reject  Preformation 

another/'  In  such  cases,  which  are  repeated  over  and 
over,  there  is  no  escape  from  the  admission  that  with 
the  progress  of  growth  there  has  taken  place  in  the 
blended  organs  a  sort  of  smoothing  out,  "Ausglattung," 
of  the  external  and  internal  walls,  and  perhaps  even  a 
transitory  modification  of  the  normal  form,  caused  simply 
by  the  influence  of  the  similar  organs  growing  together.98 

In  other  cases  there  is  more  than  a  simple  smoothing 
out  of  the  two  surfaces  which  would  not  fit  together 
at  first.  Thus  in  the  union  of  two  parts  of  the  intestine 
of  double  monsters,  thoracopagi,  gastropagi,  and  ventro- 
pagi,  obtained  by  cutting  off  from  each  of  two  tadpoles 
a  thin  layer  of  the  abdomen,  and  superimposing  the  two 
cut  surfaces  as  usual,  there  results  an  exact  conjunction 
of  the  two  thin-walled  intestinal  tubes  in  such  a  man- 
ner as  to  constitute  a  single  tube  without  any  trace  of 
the  junction  which  was  made.  So  exact  a  coaptation 
can  certainly  not  be  effected  by  the  simple  superposition 
of  the  two  tadpoles." 

Sometimes  the  corresponding  organs  of  the  two 
larvae  seem  as  though  seeking  each  other  and  reaching 
out  to  each  other.  They  both  deviate  from  their  ordinary 
direction  in  order  to  be  able  to  unite  and  extend  one 
into  the  other.  This  phenomenon  appears  character- 
istically in  the  fusion  of  the  two  vascular  systems  as  is 
demonstrated  in  the  clearest  manner  by  certain  experi- 
ments in  grafting  definite  portions  of  tadpoles  upon 
complete  tadpoles:  as  for  example,  the  grafting  of  the 
posterior  heartless  portion  of  a  tadpole  upon  the  abdomen 
of  another  complete  tadpole:  the  fusion  of  the  two  vas- 
cular systems  is  so  complete  that  a  single  blood  circulation 

MG.  Born:  Ibid.    P.  141. 
"G.  Born :  Ibid.    P.  69—86. 


Form  Not  Dependent  on  Number  of  Divisions    131 

is  produced,  the  heart  of  the  complete  tadpole  putting 
in  circulation  the  blood  of  the  grafted  portion  also.100 

This  phenomenon  is  presented  also  very  strikingly 
in  the  mutual  prolongation  one  into  another  of  the 
pronephric  and  other  secretory  ducts.  Thus  in  a  double 
monster  obtained  by  uniting  the  anterior  portions  of  two 
tadpoles,  the  left  pronephric  ducts  met  and  grew  together 
although  at  first  their  extremely  fine  cut  ends  certainly  lay 
some  distance  apart  and  their  directions  crossed  almost  at 
right  angles.101 

All  these  phenomena  are  hard  to  reconcile  with  the 
rigidity  implied  in  Weismann's  determinants.  They 
speak  on  the  contrary  entirely  in  favor  of  a  general 
process  of  growth  that  is  epigenetic  in  nature;  for  only 
to  a  process  of  growth  of  this  nature  can  be  ascribed 
all  the  phenomena  of  adaptation  and  of  deviation  from 
the  normal  form  which  result  in  the  complete  and  exact 
conjunction  of  the  various  corresponding  portions  of 
different  individuals. 

Against  the  rigid  preformation  of  Weismann,  which 
attributes  development  exclusively  to  qualitative  nuclear 
divisions,  Roux  himself  furnishes  a  most  appropriate 
argument  which  even  the  most  pronounced  anti-preform- 
ists  rarely  cite. 

"In  the  larger  animals  of  the  same  species  the  cells 
are  not  correspondingly  larger  than  in  individuals 
which  in  consequence  of  lack  of  nourishment  have  re- 
mained smaller.  Thus  the  unequal  size  of  the  individuals 
must  be  associated  with  an  unequal  number  of  cell 
divisions,  which  by  the  method  of  qualitative  differentia- 
tion assumed  by  Weismann  must  lead  to  a  very  essential 

100G.  Born :  Ibid.    P.  87—88. 
101G.  Born:  Ibid.    P.  144. 


132    Facts  Compelling  Us  to  Reject  Pre formation 

disturbance.  It  follows  that  qualitative  differentiation 
can  not  have  any  close  association  with  the  number  of 
cell  divisions,  nor  indeed  with  the  process  of  cell  division 
itself,  so  that  it  is  not  possible  for  any  definite  qualitative 
alteration  to  be  so  associated  with  each  individual  cell 
division  as  to  produce  a  definite  character  in  each  soma- 
tic cell  of  the  tenth,  eleventh,  twelfth,  twentieth,  and 
fiftieth  generation  from  the  egg  cell  in  consequence  of 
this  number  of  generations."  102 

To  circumvent  this  objection  to  the  preformation 
theory,  Roux  has  recourse  to  the  hypothesis  of  a  self 
regulating  mechanism  of  frankly  epigenetic  nature 
which  really  amounts  to  reducing  the  part  played  by 
preformative  processes  in  ontogeny  to  a  wholly 
subordinate  role.103 

But  the  strongest  objections  against  preformation 
are  on  the  one  hand  the  above  mentioned  experiments 
on  isolation  of  blastomeres,  and  the  production  of 
double  monsters  from  a  single  egg  and  other  similar  ones, 
and  on  the  other  hand  the  experiments  upon  regeneration. 

The  experiments  upon  the  isolation  of  blastomeres 
which  showed  that  each  one  could  produce  an  entire 
individual  are,  as  we  have  already  explained  in  the  pre- 
ceding chapter,  a  convincing  proof  that  at  least  the  first 
nuclear  divisions  are  not  qualitatively  unequal.  Having 
recourse  to  a  reserve  idioplasm  implies  the  renuncia- 
tion of  preformist  theories.  For  in  the  first  place,  it 
really  admits  that  the  whole  of  the  idioplasm  (active 

a°2Wilhelm  Roux:  Uber  die  Bestimmung  der  Hauptrichtungen 
des  Froschembryo  im  Ei  und  iiber  die  erste  Teilung  des  Froscheies. 
Sep.-Abdruck  aus  der  Breslauer  arztlichen  Zeitschrift,  1885,  P.  35. 
Gesamm.  Abhandl.  II.  P.  316 — 317. 

103Wilhelm  Roux:  Ibid.  P.  35,  317. 


Double  Formations  133 

plus  reserve  idioplasm)  remains  after  division  just  as 
it  was  before;  in  the  second  place,  the  conception  by 
which  one  makes  the  activation  or  non-activation  of 
the  reserve  idioplasm  depend  upon  the  abnormal  or  nor- 
mal relations  of  the  different  nuclei  with  one  another  is 
very  similar  to  that  of  epigenesis  with  preformistic  germs, 
such  as  would  correspond  somewhat  with  the  hypothesis 
of  DeVries  or  that  of  Oscar  Hertwig. 

The  formation  of  double  monsters  from  a  single 
egg  constitutes  essentially  an  analogous  case  to  that  of 
the  formation  of  entire  individuals  from  isolated  blasto- 
meres.  We  mention  for  example  the  experiments  of 
Wilson  in  which  following  the  simple  displacement  in 
relation  to  each  other  of  the  first  two  blastomeres  of 
the  egg  of  Amphioxus,  each  of  those  blastomeres  pro- 
duced a  gastrula  united  along  a  more  or  less  extensive 
surface  with  the  gastrula  produced  by  the  other  blasto- 
mere  in  such  a  manner  as  to  give  rise  to  numerous  and 
very  varied  forms  of  double  gastrulas  in  which  the 
axes  and  respective  blastopores  of  the  twin  gastrulas 
were  oriented  in  the  most  diverse  ways  in  relation  to  one 
another.104  The  same  thing  occurred  in  the  similar 
double  monsters  obtained  by  Oscar  Schultze  from  frogs' 
eggs,  which  were  produced  by  compressing  the  egg  be- 
tween two  horizontal  plates  and  turning  them  over 
immediately  after  the  first  segmentation.105 

If  these  double  monsters, — and  Roux  has  remarked 

104E.  B.  Wilson:  Amphioxus  and  the  Mosaic-Theory  of  Devel- 
opment. Journ.  of  Morphology,  vol.  VIII,  No.  3.  Boston,  U.  S.  A., 
Ginn.  August  1893;  P.  591—595-  Table  XXXIV. 

106O.  Schultze :  Die  kiinstliche  Erzeugung  von  Doppelbildungen 
bei  Froschlarven  mit  Hilfe  abnormer  Gravitationswirkung.  Arch.  f. 
Entwicklungsmech.  d.  Organismen  Bd.  I.  Heft  2.  Leipzig,  Engel- 
mann,  1894.  P.  276—284.  Tables  XI  and  XII. 


134    Facts  Compelling  Us  to  Reject  Pre formation 

this  himself,  as  we  have  seen  in  the  case  of  those  with 
double  symmetry, — are  opposed  on  one  side  to  simple 
epigenesis  because  they  show  that  between  the  two 
organisms,  even  though  they  have  so  great  a  part  of 
the  body  in  common  there  do  not  exist  any  general 
reciprocal  actions  tending  to  make  a  single  whole  of  the 
two  bodies,  they  are  on  the  other  side,  also  opposed  to 
pre formation,  in  that  they  demonstrate  in  the  same  man- 
ner as  do  the  experiments  upon  isolation  of  blastomeres, 
the  equipotency  or  qualitative  identity  of  the  two  first 
segmentation  nuclei. 

And  this  equipotency  is  not  limited  only  to  the  two 
first  but  exists  also  in  all  the  first  blastomeric  nuclei  as  is 
demonstrated  by  the  inverse  phenomenon  obtained  by 
Morgan  of  the  formation  of  a  single  embryo  from  two 
blastulas  of  Sphaerechinus  which  had  grown  together  of 
themselves.106 

Finally  preformation  as  we  have  said,  is  quite  irrecon- 
cilable with  all  the  manifold  processes  of  regeneration 
without  exception. 

Above  all,  Weismann  interprets  in  fundamentally  the 
same  sense  as  we,  the  experiments  and  observations  of 
Roux  upon  the  peculiar  regeneration  constituted  by  the 
postgeneration  or  completion  of  the  half  embryos  which 
we  have  so  often  mentioned.  For  they  signify  as  he 
himself  admits,  "that  this  completion  took  place  by  a  kind 
of  cell  infection,  of  such  a  nature  that  mere  contiguity,  for 
example  with  ectoderm  cells,  caused  the  as  yet  undifTeren- 
tiated  cells  of  the  side  operated  upon  to  become  developed 
into  ectodermal  cells,  while  similar  contiguity  with  me- 

10<5E.  H.  Morgan:  The  Formation  of  one  Embryo  from  two 
Blastulae.  Arch.  f.  Entwicklungsmech.  d.  Org.,  1895.  Bd.  II.  Heft 
I.  P.  65—71. 


Remodeling  of  Old  Tissues  in  Regeneration     135 

soblastic  cells  made  them  become  mesoblastic  cells/'  And 
Weismann  finally  calls  into  question  the  incontestability 
of  these  facts,  just  because  such  a  cell  determination  de- 
pendent upon  contiguity  would  upset  at  once  his  whole 
theory  of  preformation.107 

But  there  are  also  many  cases  of  regeneration  proper 
in  which  one  has  a  remodeling  of  old  tissues  into  new 
tissues  that  are  quite  different,  and  they  constitute 
phenomena  which  are  analogous  in  this  respect  with  post- 
generation.  As  an  example  may  be  mentioned  the 
regeneration  of  Planaria  maculata. 

Fragments  of  this  worm  "obtained  by  two  transverse 
sections  regenerate  the  head  and  the  tail  by  producing 
new  cells.  But  after  their  formation,  this  head  and  this 
tail  do  not  grow  any  further,  but  the  entire  subsequent 
growth  in  length  of  the  body  takes  place  in  the  older  more 
pigmented  parts,  so  that  the  normal  relative  proportions 
of  the  planaria  are  restored  simply  by  a  remodeling  of  the 
older  tissues.  "The  fragment  of  the  worm  reacquires  its 
normal  form  but  not  through  the  addition  of  new  tissue 
at  the  anterior  and  posterior  extremities,  except  to  a  very 
small  extent.  The  transformation  is  produced  chiefly  in 
the  old  tissue  after  the  head  and  tail  are  developed.  Thus 
we  find  here  not  only  the  capacity  of  regeneration  but 
also  a  subsequent  self-regulation  by  means  of  which  the 
normal  relations  of  the  parts  characteristic  for  the  species 
become  re-established/'  But  that  is  not  all.  For  in  an- 
imals regenerated  from  lateral  fragments,  the  longitudinal 
axis  of  the  new  worm  is  found  often  in  the  older  tissue, 
so  that  one  portion  of  the  old  material  which  was  in  the 
right  side  of  the  old  animal  becomes  now  part  of  the  left 

10TWeismann:  Das  Keimplasma.     P.  192. 


136    Facts  Compelling  Us  to  Reject  Prefonnation 

side  of  the  new  animal  or  vice  versa ;  and  the  development 
of  the  new  pharynx  which  is  found  in  the  exact  lon- 
gitudinal axis,  indicates  that  it  can  be  produced  indiffer- 
ently from  any  part  whatever  of  the  old  tissue.108 

This  remodeling  of  old  tissues  into  new  tissues  differ- 
ing from  them  indicates  that  the  supposed  determinants 
of  Weismann  have  not  by  themselves  any  value,  for  as 
soon  as  the  tissue  finds  itself  in  conditions  different  from 
the  normal  ones  it  takes  on  forms  and  acquires  properties 
which  would  require  determinants  of  quite  another  nature. 
"The  organism/'  writes  Whitman,  "dominates  cell  forma- 
tion using  for  the  same  purpose  one,  several,  or  many 
cells,  massing  its  material  and  directing  its  movements 
and  shaping  its  organs  as  if  cells  did  not  exist  or  as  if 
they  existed  only  in  complete  subordination,  if  I  may  so 
speak,  to  its  will."  10°  And  one  would  not  know  how  to 
give  any  better  proof  of  the  correctness  of  this  statement 
than  that  which  is  constituted  by  these  particular  regener- 
ations, which  utilize  the  material  already  existing  to 
remodel  it  into  the  new. 

And  not  only  are  these  phenomena  of  peculiar  regen- 
eration irreconcilable  with  preformation  but  the  very  fact 
of  regeneration  in  general  is  irreconcilable  with  it. 

"The  germ  tissue  of  the  new  organ,"  writes  Hertwig, 
"does  not  contain  any  remnant  of  the  amputated  organ 
itself  from  which  it  could  be  reproduced  by  simple 
growth.  The  buds  destined  to  reconstitute  the  eye-bear- 

108E.  M.  Morgan :  Experimental  Studies  on  the  Regeneration  of 
Planaria  maculata.  Arch.  f.  Entwicklungsmech.  d.  Org.  Bd.  VII. 
Heft  2.  and  3.  Leipzig,  Engelmann.  Oct.  18,  1898.  P.  385,  389,  395 
—396. 

"'Whitman:  The  Inadequacy  of  the  Cell-Theory  of  Develop- 
ment. Biol.  Lect.  at  the  Mar.  Biol.  Lab.  of  Wood's  Holl,  Summer 
Session  1893.  Boston,  U.  S.  A.,  Ginn  1894.  P.  119. 


Weistnann's  Accessory  Idioplasm  137 


ing  tentacles  of  the  snail  contain  no  trace  whatever  of 
retinal  cells  nor  of  pigment  cells,  nor  of  any  other  sensory 
cells  whatever.  Similarly  the  buds  for  the  extremities  do 
not  contain  any  trace  of  the  material  of  the  carpus  and 
phalanges  nor  of  the  muscles  and  tendons  belonging  to 
them.  It  is  a  complete  new  formation."  no 

The  explanation  which  Weismann  endeavors  to  give 
of  these  complete  new  formations  produced  in  every  re- 
generation is  well  known : 

"If  each  cell  of  the  completely  developed  bone  con- 
tains within  it  only  that  kind  of  idioplasm  which  con- 
trols it  and  which  is  consequently  the  molecular  expres- 
sion of  its  own  particular  nature,  it  would  be  impossible 
to  understand  how  the  regeneration  could  be  effected  of 
a  bone  which  had  been,  for  instance,  cut  through  lon- 
gitudinally. Supposing  that  because  of  the  wound  there 
would  become  exercised  upon  the  cells  of  the  stump  a 
stimulus  which  caused  them  to  proliferate,  a  mass  of  bony 
tissue  would  indeed  be  produced  but  never  a  bone  of  def- 
inite size  and  shape.  This  can  take  place  only  in  case  the 
cells  undergoing  proliferation  possess,  besides  their  ac- 
tive determinants,  an  additional  supply  of  determinants 
which  control  the  missing  part  about  to  be  reformed.  It 
is  then  evident  that,  if  we  wish  to  transport  the  Nisus 
formativus  of  Blumenbach  into  the  cell  and  indeed  into 
its  idioplasm,  we  must  assume  that  each  cell  capable  of 
regeneration  contains  besides  its  principal  idioplasm,  also 
an  accessory  idioplasm  ('Neben-Idioplasm'),  consisting 
of  the  determinants  of  the  portion  of  the  amputated  organ 
which  can  be  regenerated  by  it.  Thus,  for  instance,  the 
cells  of  the  humerus  must  contain  besides  their  own  con- 

110Oscar  Hertwig :  Die  Zelle  und  die  Gewebe.   II.   P.  180. 


138      Facts  Compelling  Us  to  Reject  Preformation 

trolling  determinants  also  all  the  determinants  of  the 
forearm  and  of  the  hand  as  accessory  idioplasm,  for  they 
can  cause  the  entire  chain  of  these  bones  to  be  formed 
anew;  and  the  cells  of  the  radius  must  contain  as  acces- 
sory idioplasm  all  the  determinants  of  the  radial  portion 
of  the  wrist,  hand  and  fingers. 

"We  can  regard  this  theoretical  requirement  as  quite 
realizable  also,  since  when  the  whole  organ  commences 
to  be  formed,  the  necessary  accessory  idioplasm  can  very 
well  separate  from  the  disintegrating  embryonic  idio- 
plasm. We  need  only  assume  that  this  accessory  idio- 
plasm remains  henceforth  inactive  in  the  nuclear  sub- 
stance of  the  cell  until  some  cause  for  regeneration 
arises."111 

We  note  at  once  that,  according  to  this  hypothesis, 
there  is  no  reason  at  all  why  there  should  be  held  in  re- 
serve in  each  part  of  the  bone  only  the  accessory  idio- 
plasm capable  of  regenerating  the  bony  parts  distal  to 
that  point,  but  never  any  other  capable  of  regenerating  a 
larger  or  smaller  part.  Each  particular  reserve  idioplasm, 
when  once  it  has  separated  itself  in  a  given  cell  from  the 
principal  idioplasm,  and  been  segregated  in  the  nucleus  of 
the  cell  itself  in  the  latent  state,  will  be  able  to  preserve 
itself  unaltered  through  many  generations  of  cells.  Con- 
sequently there  must  be  present  at  any  point  at  which  a 
bone  may  be  broken  several  accessory  idioplasms,  each 
capable  of  regenerating  a  more  or  less  long  portion  of  the 
bone  which  was  broken,  and  perhaps  also  of  some  other 
bone.  In  the  illustrative  case  cited  by  Weismann  the  sec- 
ond phalanx  should  contain  besides  the  reserve  idioplasm 
capable  of  regenerating  the  second  and  third  phalanx, 

111Weismann :  Das  Keimplasma.  P.  136 — 138. 


Regeneration  and  Generation  139 

also  that  which  is  capable  of  regenerating  all  three  pha- 
langes; or  the  distal  part  of  the  second  phalanx  should 
contain,  besides  the  accessory  idioplasm  capable  of  regen- 
erating the  distal  portions  of  the  second  phalanx  and  the 
whole  of  the  third  phalanx,  also  that  which  is  capable  of 
regenerating  both  the  third  phalanx  and  the  entire  second 
phalanx  itself.  Why,  then,  should  only  that  accessory 
idioplasm  become  activated  which  is  capable  of  regenerat- 
ing just  the  particular  part  cut  off? 

Further,  Weismann  himself  recognizes  that  when  dif- 
ferent tissues  and  organs  are  cut  through,  "it  is  only  the 
harmonious  equipment  of  the  cells  of  a  definite  cross  sec- 
tion with  groups  of  determinants,  different  but  mutually 
adaptable,  in  accord  among  themselves  and  compliment- 
ary, that  could  make  regeneration  of  the  higher  type  pos- 
sible." 112  But  really  it  is  not  easy  to  conceive  how  this 
harmonious  equipment  of  reserve  idioplasm  could  be 
guaranteed  in  the  great  number  of  different  cells  of  a 
complex  section. 

Roux  has  seen  so  clearly  this  impossibility  of  explain- 
ing the  phenomena  of  regeneration  by  pre formation 
theories,  that  he  asserts  that  in  "direct"  or  "typical"  gen- 
eration self-differentiation  may  have  the  preponderance 
over  differentiation  due  to  reciprocal  actions  among  the 
parts  without  nevertheless  entirely  excluding  it;  but  in 
regeneration,  which  he  calls  "indirect"  or  "atypical" 
generation,  he  admits  that  differentiation  of  epigenetic 
nature  must  necessarily  prevail  over  pre  formation.113 

Weismann  has  rightly  been  unwilling  to  fall  into  the 
contradiction  of  imagining  two  different  natures  for  two 

112Weisann:  Ibid.  P.  297—298. 

113Roux:  Uber  Mosaikarbeit  usw.  Anat.  Hefte.  P.  279—331. 
Gesamm.  Abhandl.  II.  P.  819—870. 


140    Facts  Compelling  Us  to  Reject  P  reformation 

processes  which  are  essentially  identical  with  each  other, 
but  has  been  thereby  driven  to  an  attempt  at  explanation, 
which  is  wholly  artificial  and  indefensible. 

In  order  to  make  the  artificiality  of  his  interpretation 
of  the  most  difficult  cases  clearer,  let  us  consider  further 
the  following  examples. 

It  is  known  that  regeneration  is  not  usually  an  exact 
repetition  of  the  ontogenetic  process. 

"Until  the  last  few  years,"  writes  Delage,  "it  has  been 
regarded  as  a  dogma  that  regeneration  is  a  repetition  of 
ontogeny.  That  is  that  the  regenerating  organ  or  limb 
goes  through  the  successive  stages  of  development 
through  which  it  went  in  its  first  formation.  Yet  the 
question  has  not  been  thoroughly  enough  investigated  to 
permit  the  statement  that  it  always  does  this,  and  in  many 
cases  it  is  certain  that  it  does  not  proceed  in  this  way. 
Thus  a  round  tailed  salamander  regenerated  a  round  tail 
from  the  first  and  not  the  flattened  finlike  tail  of  the  larva, 
the  crab  regenerates  an  adult  foot  and  not  a  foot  like  that 
of  its  larva,  Zoaea.  The  limb  or  organ  regenerated  after 
a  wound  arrives  at  once  at  the  stage  which  corresponds  to 
the  age  at  which  regeneration  takes  place."  114 

Further,  regenerations  of  ectodermic  tissues  at  the 
expense  of  entodermal  or  mesodermal  tissues  are  not 
rare.  We  have  already  seen  how  the  crystalline  lens, 
embryologically  of  ectodermic  origin,  regenerates  in  the 
triton  from  the  mesodermic  iris.  The  anterior  intestine 
of  Tubifex  rivulorum,  whose  ontogenetic  origin  is 
ectodermal,  regenerates,  with  the  exception  of  a  small 
portion  at  the  end,  from  entodermal  tissues.115 


'Delage  :  L'heredite  etc.    P.  104 — 105. 
5H.  Haase :  Uber  Regenerationsvorgar 
Lam.   mit  besonderer   Beriicksichtignng   des  Darmkanals  und   Ner- 


114] 

118H.  Haase :  Uber  Regenerationsvorgange  bei  Tubifex  rivulorum 


Regeneration  Not  Exact  Repetition 


141 


Finally,  cases  are  not  rare  in  which  a  regenerating1 
organ  alters  its  form,  as  in  the  lizard  in  which  the  new 
tail  has  a  skeleton  not  formed  of  individual  vertebrae  at 
all,  but  of  a  little  continuous,  cartilaginous  cylinder. 

Now  the  epigenetic  theories  explain  very  easily  how 
it  comes  that  the  part  amputated  can  follow  in  its  regen- 
eration a  shorter  road  than  in  its  ontogeny  (caenogenetic 
regeneration),  and  how  in  many  cases  after  completion  of 
the  process,  it  may  have  a  form  quite  different  from  that 
of  the  original  part.  For  the  remaining  part  of  the  body, 
on  which  the  morphologic  determination  of  the  ampu- 
tated part  depends,  is  now  in  the  adult  state  while  for- 
merly it  was  in  the  embryonic  state. 

The  altered  condition  in  which  it  now  exerts  its 
formative  action  upon  the  part  in  process  of  regenera- 
tion explains  the  diversity,  not  only  of  the  earlier  results 
obtained,  in  which  development  and  regeneration  proceed 
in  different  ways,  but  also  of  the  final  results,  in  which  the 
regenerated  part  is  of  abnormal  conformation.  For  the 
differences  of  conformation  which  are  produced  at  the 
commencement  of  the  process  of  regeneration  cannot 
always  be  smoothed  out  and  effaced  when,  at  the  end  of 
the  regenerative  process,  the  condition  of  the  rest  of  the 
organism  from  which  the  formative  action  is  exerted 
upon  the  part  in  process  of  regeneration  becomes  again 
the  same  in  relation  to  that  latter  as  at  the  end  of 
normal  ontogeny. 

Weismann  on  the  contrary,  whose  above  quoted  ex- 
planation is  clearly  no  more  adapted  to  these  cases,  is 
forced  to  take  refuge  in  the  following  subsidiary 
hypothesis : 

vensystems.     Zeitscher.   f.   wissensch.    Zoologie.   Bd.,  65.  Zw.   Heft, 
1898.    P.  229—235. 


142  Facts  Compelling  Us  To  Reject  Pre formation 

"In  caenogenetic  regeneration,  (and  a  fortiori  when 
the  regenerated  part  remains  of  abnormal  conformation), 
one  cannot  but  admit  that  certain  double  or  multiplied 
determinants  must  be  present  beside  one  another  in  the 
germ  plasm,  some  of  them  being  destined  to  embryonic 
development,  others  to  regeneration.  These  latter  must 
have  their  interior  forces  and  particularly  their  growing 
force  so  arranged  in  advance  as  to  split  off,  either  alone 
or  together  with  neighboring  determinants  of  regenera- 
tion, as  reserve  idioplasm,  at  the  proper  moment  of 
development."  116 

Epigenetic  theories  contain  in  themselves  an  imme- 
diate explanation  of  the  well  known  fact  that  when  a 
worm  is  cut  in  two,  the  anterior  part  regenerates  the 
posterior  while  the  posterior  regenerates  the  anterior. 

Weismann  on  the  contrary  is  forced  to  have  recourse 
to  the  following  artificial  hypothesis :  "As  the  two  halves 
become  always  complete  again,  no  matter  at  what  place 
the  worm  is  cut,  it  therefore  follows  that  the  cells  situated 
in  any  particular  transverse  planes  of  the  body  are  not 
merely  provided  with  reserve  determinants  for  generating 
in  some  planes  the  head,  in  others  the  tail,  but  every  cell 
must  be  able  to  act  in  either  way,  according  to  whether  it 
happens  to  lie  anteriorly  or  posteriorly  to  this  plane.  In 
order  therefore  to  explain  the  twofold  reaction  of  these 
cells,  and  stick  to  our  fundamental  view, — which  regards 
the  cells  concerned  in  regeneration,  as  arranged  and  con- 
trolled by  forces  lying  within  themselves,  and  not  by  any 
external  directing  power, — it  seems  to  me  that  we  must 
assume  that  each  of  them  contains  two  different  reserve 
determinants,  one  for  reconstruction  of  the  head,  the 

"'Weismann:    Das  Keimplasma.     P.  145—146,  147. 


IVeismann's  Explanation  of  Regeneration       143 

other  for  that  of  the  tail  end,  and  that  one  or  the  other 
becomes  active  according  as  the  stimulus  due  to  lying  un- 
covered, is  applied  to  the  anterior  or  posterior  surface  of 
the  cell  concerned."  117 

Finally  according  to  epigenetic  theories  the  regenera- 
tion of  the  hydra  is  a  process  which  does  not  differ  es- 
sentially from  any  other  process  of  regeneration,  but  ac- 
cording to  Weismann's  theory  the  following  complicated 
additional  explanation  becomes  necessary. 

"If  one  divides  a  hydra  in  a  longitudinal  plane  the 
two  halves  grow  again  into  entire  individuals,  irrespective 
of  the  plane  of  section.  As  a  transverse  section  of  the 
animal  at  any  point  which  may  be  selected  is  followed 
likewise  by  the  complete  reconstruction  of  each  of  the 
two  halves  it  follows  that  every  part  of  the  body  of  the 
hydra  must  be  capable  of  regeneration  in  a  threefold 
direction,  namely  in  the  three  directions  of  space.  As  the 
body  is  differently  constructed  in  these  three  directions 
we  are  forced  to  the  conclusion  that  each  of  its  cells  must 
contain  groups  of  determinants  of  three  different  kinds. 
*  *  *  And  it  cannot  be  the  quality,  but  the  direction 
from  whicfi  the  stimulus  of  the  wound  comes  to  each 
cell,  which  will  decide  for  it  which  of  the  three  groups  of 
determinants  will  become  active."  118 

We  believe  that  we  do  not  pronounce  too  severe  a 
judgment,  if  we  affirm  that  so  artificial  a  hypothesis 
demonstrates  the  absolute  incompetency  of  preformation 
theories  to  explain  the  phenomena  of  regeneration. 


What  is  the  conclusion  which  can  be  drawn  from  all 
that  we  have  said  thus  far  in  the  present  chapter? 

117Weismann :  Das  Keimplasma.   P.  169. 
L18Weismann :  Das  Keimplasma.    P.  170. 


144  ^  Homogeneous  Germ  Substance  Inadmissable 

The  first  part  has  shown  us  that  simple  epigenesis  is 
directly  and  decidedly  controverted  by  a  whole  series  of 
indubitable  facts  and  results  which  no  one  now  opposes. 
The  second  part,  which  refutes  preformation,  shows  us 
on  the  contrary  that  the  nature  of  every  process  of 
development  is  really  epigenetic. 

And  thus  a  correspondingly  greater  probability  is  es- 
tablished for  those  hypotheses  which,  concentrating  the 
power  of  sending  forth  the  controlling  influences  of 
development  into  a  single  wrell  defined  zone  of  the  orga- 
nism, thereby  explain  quite  as  well  as  epigenesis  the  facts 
that  are  irreconcilable  with  preformation,  and  are  at  the 
same  time  in  accord  also  with  all  the  facts  which  simple 
epigenesis  is  incapable  of  explaining. 

j.     Inadmissibility  of  a  Homogeneous  Germinal 
Substance 

It  will  not  be  necessary  to  give  this  question  more 
than  a  very  brief  consideration,  for  it  is  sufficient  to  men- 
tion the  chief  argument  which  all  the  partisans  of  pre- 
formistic  germs,  the  epigenesists  as  well  as  the  preform- 
ists  proper,  have  repeated  incessantly  and  still  repeat. 
The  fact  that  in  doing  this  each  uses  almost  the  same  ex- 
pressions as  the  others  shows  how  conclusive  this 
argument  is. 

"The  considerations,"  remarks  Wilson,  "which  have 
led  to  the  rehabilitation  of  the  theory  of  pangenesis  are 
based  upon  the  facts  of  what  Galton  has  called  particu- 
late  inheritance.  The  phenomena  of  atavism,  the  char- 
acters of  hybrids,  the  facts  of  spontaneous  variation,  all 
show  that  even  the  most  minute  characteristics  may  ap- 
pear or  disappear  independently,  may  be  modified  inde- 


P articulate  Inheritance  145 

pendently,  may  be  inherited  independently  from  either 
parent,  without  in  any  way  disturbing  the  equilibrium  of 
the  organism,  or  showing  any  correlation  with  other 
variations.  These  facts,  it  is  argued  (by  the  partisans  of 
pre formation),  compel  us  to  believe  that  hereditary  char- 
acters are  represented  in  the  idioplasm  by  distinct  and 
definite  germs  (pangens,  idioblasts,  biophores,  etc.), 
which  may  vary,  appear  or  disappear,  become  active  or 
latent,  without  affecting  the  general  architecture  of  the 
substance  of  which  they  form  a  part.  Under  any  other 
theory  we  must  suppose  variations  to  be  caused  by 
changes  in  the  molecular  composition  of  the  idioplasm  as 
a  whole,  and  no  writer  has  shown  even  in  the  most  ap- 
proximate manner  how  particulate  inheritance  can  thus 
be  conceived."  119 

It  is  well  known  that  this  is  really  the  principal  argu- 
ment, one  might  say  the  only  one,  which  Galton  brings 
up  in  defense  of  his  germs,  substituted  by  him  for  the 
gemmules  of  Darwin:  "The  independent  origin  of  the 
several  parts  of  the  body  can  be  argued  from  the  separate 
inheritance  of  their  peculiarities.  If  a  child  has  its 
father's  eyes  and  its  mother's  mouth  these  two  features 
must  have  had  a  separate  origin.  Now,  it  is  observed  that 
peculiarities  even  of  a  microscopic  kind  are  transmissible 
by  inheritance,  therefore  it  may  be  concluded  that  the 
most  minute  parts  of  the  body  have  separate  origins."  12° 

The  argument  which  DeVries  brings  up  in  favor  of 
his  pangens,  or  material  particles  representative  of  the 

119E.  E.  Wilson:  The  Mosaic  Theory  of  Development.  Biol. 
Lect.  at  the  Mar.  Biol.  Lab.  of  Wood's  Holl :  Summer  Session  1893. 
Boston,  U.  S.  A.,  Ginn,  1894.  P.  3 — 4. 

l20Francis  Galton :  A  Theory  of  Heredity.  Journ.  of  the  Anthro- 
pological Institute.  January  1876.  P.  331. 


146  A  Homogeneous  Germ  Substance  Inadmissible 

different  characters  of  the  organism,  is  quite  similar  to 
that  of  Galton.  It  is  summed  up  in  the  following  passages 
from  his  book:  "Many  species  of  plants,"  writes  he, 
"have  the  power  of  producing  definite  chemical  com- 
pounds :  among  the  most  important  of  these  are  the  red 
and  blue  coloring  substances  of  flowers :  also  the  various 
tannic  acids,  the  alkaloids,  the  etherial  oils,  and  numer- 
ous other  products.  A  small  number  only  of  these  com- 
pounds are  limited  to  a  single  species  of  plants :  a  large 
number  are  present  in  two  or  more  species,  systematically 
far  removed  from  one  another.  There  is  no  reason  to 
believe  that  there  is  a  different  mode  of  production  of  the 
same  compound  in  each  particular  case :  on  the  contrary 
one  would  naturally  expect  the  same  compound,  in  what- 
ever place  one  meets  it,  to  be  produced  always  by  the 
same  chemical  mechanism/' 

"Similarly  we  must  admit  the  possibility  of  a  break- 
ing down  of  the  morphologic  signs  of  species.  Morphol- 
ogy is  clearly  not  yet  far  enough  advanced  to  permit  of 
such  an  analysis  in  each  particular  case.  But  the  same 
coarse  or  fine  notching  at  the  leaf  margins  are  repeated 
in  numerous  species  and  the  customary  terminology  in- 
forms us  in  advance  that  all  forms  of  leaf  patterns  are 
composed  of  a  relatively  small  number  of  more  simple 
characters." 

"This  shows  that  the  character  of  each  individual 
species  is  made  up  of  numerous  hereditary  peculiarities  of 
which  the  most  part  are  present  also  in  an  almost  infinite 
number  of  other  species.  *  *  *  According  to  this 
view,  we  would  regard  each  species  as  an  extremely  com- 
plicated figure,  and  the  organic  world  in  its  entirety  as  the 
result  of  innumerable  different  permutations  and  com- 
binations of  a  relatively  small  number  of  factors." 


Independence  of  Hereditary  Peculiarities       147 

"  Experiments  upon  the  production  of  varieties  teaches 
us  further  that  nearly  every  peculiarity  can  vary  inde- 
pendently of  the  others.  Many  varieties  in  fact  diverge 
from  their  stock  form  by  only  a  single  character ;  for  in- 
stance the  white  blooming  variety  of  a  species  with  red 
flowers.  In  the  same  way  the  villosity,  the  armanent  of 
spines  or  thorns,  the  green  color  of  leaves,  each  of  these 
characters  can  vary  by  itself  and  can  even  disappear  en- 
tirely, and  all  the  other  hereditary  properties  remain 
perfectly  unaltered." 

It  follows  that:  'The  hereditary  anlagen,  of  which 
the  hereditary  peculiarities  are  the  visible  signs,  are  inde- 
pendents units  which  may  have  had  their  origin  at  differ- 
ent epochs,  and  which  may  also  be  lost  independently. 
They  are  miscible  with  one  another  in  almost  all  propor- 
tions, since  each  peculiarity  can  pass  through  all  inter- 
mediate degrees  from  its  complete  absence  to  its  greatest 
development." 

"Independence  and  miscibility,  these  are  the  essential 
properties  of  the  hereditary  anlagen  of  all  organisms."  121 

Quite  similar  to  this  argument  of  DeVries  is  that  of 
Weismann  in  favor  of  his  preformation  or  of  preformistic 
germs  in  general:  "It  is  impossible  for  one  part  of  the 
body  to  vary  independently  of  the  others,  and  for  these 
variations  to  be  hereditary,  if  it  is  not  represented  in  the 
germ  plasm  by  a  special  particle,  a  variation  of  which  in- 
duces a  corresponding  variation  of  the  part  in  question. 
If  this  were  represented,  together  with  other  parts  of  the 
body,  by  a  single  particle  of  the  germ  plasm,  then  a 
change  of  this  latter  would  have  as  its  consequence  the 
variation  of  all  the  parts  which  are  determined  by  it.  In 

121De  Vries:  Intracellulare  Pangenesis.  Jena,  Fischer,  1889.  P. 
8— 9,  17,  32,  33.  English  Translation  by  C.  Stuart  Gager.  Open 
Court  Publishing  Co.  1910. 


148  A  Homogeneous  Germ  Substance  Inadmissible 

those  parts  of  the  body  which  are  independently  and 
hereditarily  variable,  we  have  thus  an  exact  measure  for 
determining  the  number  of  the  little  vital  particles  which 
must  compose  the  germ  plasm :  they  cannot  be  fewer." 

"We  are  then  logically  forced  to  assume  that  a  special 
element  exists  in  the  germ  plasm  for  each  of  these  pecul- 
iarities, not  because  the  inheritance  of  even  the  smallest 
details  is  possible,  but  because  each  of  these  parts  of  the 
body  can  have  its  variations  inherited  individually,  each 
by  itself.  If  all  men  possessed  a  certain  depression  in 
front  of  the  ear,  one  could  not  conclude  that  because  it 
was  hereditary,  it  must  be  represented  in  the  germ  plasm 
by  a  special  element  *  *  *  the  fact  which  forces  us 
to  accept  this  hypothesis  is  that  all  men  do  not  possess  this 
depression,  that  we  can  imagine  two  people  who  resemble 
each  other  in  all  other  respects  but  of  whom  one  pos- 
sesses this  depression  and  the  other  does  not." 

This  is  then  the  great  and  only  argument  of  all  the 
theories  of  preformistic  germs. 

One  cannot  fail  to  see  that  it  really  possesses  a  very 
great  value  against  such  theories  as  that  of  Spencer,  \vho 
supposes  the  germ  plasm  to  be  constituted  by  a  homogene- 
ous substance.  In  the  almost  complete  darkness  in  which 
we  still  find  ourselves  in  respect  to  the  nature  and  causes 
of  ontogenetic  phenomena,  there  are  very  few  things 
which  we  can  venture  to  call  impossible.  Nevertheless 
the  supposition  which  is  implied  in  the  epigenetic  theories 
of  the  Spencer  type,  namely,  that  a  homogeneous  germ 
substance  a  little  different  chemically  from  an  other,  is 
able  to  give  rise  to  an  individual  quite  identical  with  that 
which  the  other  substance  produces,  except  for  one  little 

122Weismann :  Das  Keimplasma,   P.  72 — 74. 


Theories  of  Chemical  Development  149 

peculiarity  hi  a  definite  part  of  the  organism,  if  it  does  not 
seem  quite  impossible,  certainly  seems  difficult  to  con- 
ceive. It  is  true  that  these  theories  of  the  Spencer  type 
can  always  bring  up  the  objection  that  to  a  visible  varia- 
tion of  a  certain  group  of  cells  there  might  possibly  cor- 
respond similar  variations  in  all  the  other  cells  of  the 
organism,  but  always  so  small  that  they  are  not  appre- 
ciable. But  such  an  explanation  of  the  especially  inherit- 
able variations  would  be  formal  rather  than  actual. 

This  applies  equally  well,  it  may  here  be  said  paren- 
thetically, to  evolutionary  theories  without  preformed 
germs,  such  for  example  as  the  theories  which  are  called 
those  of  the  chemical  development  of  the  egg.  They  start 
out  usually  with  a  heterogeneous  germ  substance,  con- 
stituted by  multiple  and  diverse  chemical  substances,  from 
chemical  interactions  of  which  new  chemical  compounds 
are  formed  later,  which  give  place  in  their  turn, — in  each 
cell  as  in  a  separate  crucible  independent  of  the  others, — 
to  new  chemical  reactions  and  consequently  to  new  com- 
pounds different  in  the  different  cells,  and  so  on  up  to  the 
end  of  development.  But  one  cannot  conceive  how  each 
one  of  these  components  of  the  germ  substance,  which 
commences  to  exercise  its  chemical  action  upon  the  other 
constituents  from  the  very  first  moment  of  development, 
even  though  it  be  the  only  point  in  which  one  germ  differs 
from  another,  can  bring  about  an  alteration  of  the  or- 
ganism limited  to  a  single  point  rather  than  an  alteration 
extended  over  the  entire  organism. 

The  argument  brought  up  by  the  partisans  of  pre- 
formistic  germs,  both  epigenesists  and  preformationists 
properly  so  called,  is  then  really  weighty  enough  to  force 
us  to  hold  as  inadmissible  every  biogenetic  hypothesis 
which  starts  out  from  or  is  based  upon  a  homogeneous 


150          Inadmissibility  of  Preformistic  Germs 

germinal  substance,  even  though  it  were  as  complex  as 
one  could  imagine ;  and  a  germ  substance  which  is  hetero- 
geneous indeed  but  each  of  whose  components  would 
nevertheless  commence  to  be  active  from  the  very  first 
moment  of  development  must  be  no  less  certainly 
excluded. 

On  the  other  hand  we  ask :  Is  it  in  general  possible  to 
conceive,  much  less  accept,  these  preformistic  germs,  of 
which  each  is  set  apart  for  some  infinitesimal  part  of  the 
body, — any  part  provided  that  it  can  vary  independently 
of  the  others?  Would  the  supposition  of  germs  of  this 
nature  constitute  any  explanation  whatever  of  this  par- 
ticulate  inheritance,  or  would  this  not  rather  be  a  pure 
and  simple  repetition  in  other  words  of  the  phenomenon 
which  one  pretends  to  explain? 

That  is  what  we  propose  to  consider  very  briefly  in 
the  following  last  section  of  this  chapter. 

4.     Inadmissibility  of  Preformistic  Germs 

We  note  in  advance  that  the  independently  variable 
and  inheritable  peculiarities  of  the  organism  are  not 
limited  merely  to  the  form  and  structure  of  entire  groups 
of  cells,  but  can  include  even  the  chemical  characters  of 
each  cell.  One  would  arrive  thus  at  the  absurdity  that 
not  only  each  cell,  as  Darwin's  pangenesis  already  admits, 
but  almost  each  molecule  of  the  organism  must  have  its 
representative  in  the  germ  plasm. 

Besides  this  material  impossibility  the  idea  of  pre- 
formistic germs  encounters  insurmountable  difficulties 
from  the  point  of  view  of  their  conceivability. 

Is  it  a  conceivable  thing  that  there  is  for  instance  a 
preformistic  germ  of  a  certain  nervous  tic,  or  of  a  par- 


Instincts  and  Particulate  Inheritance  151 

ticular  instinct,  that  there  is  a  pangen  or  a  group  of 
pangens  for  the  instinct  of  the  hunting  dog,  that  there  is 
a  determinant  or  group  of  determinants  of  the  instinct  of 
the  new-born  chick,  which  knows  already  how  to  peck  at 
the  wheat  and  swallow  it  ?  How  can  we  conceive  of  these 
instincts  which  are  the  consequences  of  very  complicated 
combinations  and  interconnections  of  almost  innumerable 
centers  and  nerve  tracts,  as  due  to  one  separate  germ, 
which  having  come  up  at  the  opportune  moment  of  on- 
togeny, and  at  the  exact  point  of  the  organism,  produces 
them  by  itself,  automatically,  and  we  may  say  independ- 
ently of  all  the  rest  of  the  organism  already  formed? 

And  yet  these  instincts  actually  constitute  variable 
and  inheritable  peculiarities  of  the  organism,  susceptible 
of  being  present  or  absent  independently  of  all  the  other 
peculiarities  of  the  organism.  But  if,  in  order  to  explain 
this  "particulate  inheritance"  one  has  recourse  to  germs 
especially  preformed  just  for  this,  would  this  constitute 
anything  else  than  a  purely  verbal  explanation  without 
any  real  inherent  significance? 

"A  man,  for  example,"  Le  Dantec  very  rightly  says, 
"is  composed  of  about  sixty  trillions  of  cells,  and  he  is 
nevertheless  reproduced  by  sexual  elements  of  very  small 
size :  this  is  the  phenomenon  to  be  explained.  It  has  been 
thought  that  the  difficulty  would  be  less,  or  at  least  would 
not  appear  so  distinctly,  if  one  were  to  divide  the  problem 
into  sixty  trillion  parts,  if  one  could  replace  the  reproduc- 
tion of  the  man  by  sixty  trillions  partial  reproductions; 
and  there  have  been  consequently  imagined  infinitely 
small  particles  which  are  to  the  cells  as  the  whole  germinal 
substance  is  to  the  man."  123 

1JJ8Le  Dantec:  Traite  de  Biologic.  P.  224—22^. 


152          Inadmissibility  of  Preformistic  Germs 

The  consequence  of  this  has  been  that  the  problem  has 
become  enormously  complicated  because  it  has  given  birth 
to  this  other  very  great  problem:  How  comes  it  that 
these  sixty  trillions  of  autonomous  and  therefore  inde- 
pendent individual  parts  can  constitute  a  complete  and 
harmonious  whole? 

It  results  from  this  that  preformistic  germs,  which  by 
themselves  are  quite  inadmissible,  become  yet  more  so 
when  they  are  separated  from  preformistic  doctrines 
properly  so  called.  And  Weismann  endeavored  to  show 
that  they  are  inseparable. 

"DeVries,"  he  says,  "once  mentions  the  zebra  stripes. 
How  can  such  a  character  be  transmissible  if  in  the  germ 
the  different  pangens  are  free  one  beside  another,  without 
being  bound  up  into  firm  groups  inheritable  as  such? 
Zebra-pangens  cannot  give  it,  for  the  striping  of  the  zebra 
is  no  cell  character.  Perhaps  there  are  pangens  which  for 
brevity  we  can  call  "whites"  or  "blacks/'  whose  presence 
would  produce  white  or  black  color  in  the  cell.  But  the 
striping  of  the  zebra  does  not  consist  in  the  development 
of  the  black  or  of  the  white  in  the  interior  of  the  cell,  but 
rather  in  regular  alternations  of  thousands  of  black 
or  white  cells  arranged  so  as  to  form  stripes." 

"DeVries  mentions  also  the  long  stemmed  variety  of 
the  alpine  Primula  acaulis  occasionally  produced  by 
atavistic  return  to  a  remote  stem  form.  Here  again  the 
character  of  the  long  stem  cannot  be  due  to  'long  stem 
pangens/  because  the  long  stem  is  not  an  intracellular 
property ;  neither  is  the  specific  form  of  the  leaves,  etc. ;  the 
dentate  border  of  a  leaf  cannot  be  due  to  the  presence  of 
'dentate  pangens/  but  is  due  to  a  special  arrangement  of 
the  marginal  cells.  The  same  is  true  of  nearly  all  the 
characters  which  we  designate  as  visible  properties  of  the 


Incapable  of  Explaining  Participate  Inheritance  153 

species,  genus,  or  family  etc.,  and  so  of  the  size,  struc- 
ture, and  shape  of  a  leaf,  of  the  characteristic  and  often 
constant  spots  upon  the  leaflets  of  flowers  (orchids,  and  so 
on).  All  these  properties  manifest  themselves  only  by  the 
orderly  cooperation  of  many  cells.  Or  think  of  the  prop- 
erties of  the  human  individual,  of  the  form  of  the  skull, 
of  the  nose,  and  so  on.  All  these  very  characteristic 
properties  cannot  be  due  only  to  the  presence  in  the  germ 
of  pangens  which  must  form  the  hundreds  and  thousands 
of  different  cells  which  compose  the  property  in  question ; 
they  must  be  due  rather  to  a  fixed  grouping  of  the  pan- 
gens  or  of  some  other  corresponding  primary  element  of 
the  protoplasm,  transmissible  in  its  fixity  from  generation 
to  generation."  124 

But  when  under  the  pressure  of  logical  necessity  we 
pass  from  simple  preformistic  germs,  either  free  or  in- 
termingled in  any  way,  to  germs  built  up  together  into  a 
fixed  structure,  we  fall  at  once  into  all  the  difficulties  and 
contradictions  of  pure  Weismannian  pre formation,  which 
we  have  already  discussed,  beginning  with  the  one  which 
we  have  seen  to  present  itself  first,  namely  that  it  is  quite 
inexplicable  how  this  "fixed  grouping  of  the  pangens"  can 
divide  in  successive  germ  plasms  and  nevertheless  remain 
unaltered  in  its  structure. 

Preformed  germs,  materially  impossible  and  theoreti- 
cally inconceivable,  are  nothing  else  than  empty,  wordy 
names,  and  appear  besides  to  be  quite  incapable  of  ex- 
plaining even  the  most  important  phenomena  of  particu- 
late  inheritance  on  account  of  which  they  were  especially 
devised,  and  which  constitute  the  only  excuse  for  their 
existence,  when  once  they  are  separated  from  the  stronger 

lf*Weismann :    Das  Keimplasma.     P.  22 — 23. 


154          Inadmissibility  of  Preformistic  Germs 

preformisflc    theories,    the    absolute    inadmissibility    of 
which  we  have  seen  above. 

#     *     * 

What  conclusion  can  be  drawn  from  the  last  two  sec- 
tions of  the  present  chapter  ? 

The  penultimate  section  has  shown  us  that  the  actual 
independence  in  variation  and  inheritance  of  the  various 
and  particular  characters  of  all  the  rest  of  the  organism 
can  be  explained  neither  by  a  homogeneous  germ  sub- 
stance, nor  by  a  heterogeneous  germ  substance  of  which 
all  the  various  constituents  would  become  active  from  the 
first  moment  of  development.  The  last  section  has  dem- 
onstrated to  us  the  inadmissibility  of  preformistic  germs 
although  at  first  they  appear  to  constitute  the  most  im- 
mediate explanation  of  the  mutual  independence  of  the 
various  particular  characters. 

It  remains  then  for  us  to  see  if  a  heterogeneous  germ 
substance  without  preformistic  germs,  but  whose  con- 
stituent parts  instead  of  entering  all  into  action  from  the 
first  moment  of  development,  become  active  successively 
from  the  commencement  to  the  end  of  development,  can 
give  the  adequate  explanation  of  particulate  inheritance 
which  we  are  seeking. 

Let  us  consider  first  the  phenomena  of  particulate 
inheritance  which  are  shown  by  the  presence  in  the  child 
of  certain  paternal  characters  simultaneously  with  other 
maternal  characters,  intermingled  but  yet  clearly  distin- 
guishable from  one  another.  For  the  sake  of  clearness 
we  shall  overlook  for  the  moment  all  sexual  peculiarities 
and  limit  ourselves  to  considering  only  the  clearly  asexual 
paternal  and  maternal  characters.  "The  form  of  the 
skull,"  remarks  Weismann  for  instance,  "can  be  paternal 
and  the  face  maternal;  the  form  of  the  entire  head  and 


Successively  Activated  Specific  Elements        155 

the  face  can  be  maternal  and  the  eyes,  in  spite  of  that,  be 
entirely  paternal  in  character ;  the  dimple  which  the  father 
had  on  his  chin  may  be  found  again  in  the  child,  although 
in  the  form  of  its  face  and  nose  it  may  resemble  the 
mother  rather  than  the  father."  125 

Let  us  note  at  the  same  time  that  the  germ  substance 
of  the  fertilized  egg  must  contain  the  anlagen  of  both  the 
paternal  and  maternal  germ  substance,  and  that  the 
former  as  well  as  the  latter,  since  they  correspond  one  to 
another  in  pairs,  tend  to  become  active  in  pairs  simulta- 
neously or  almost  simultaneously,  except  in  the  cases 
where  they  are  of  such  nature  as  to  be  reciprocally 
exclusive. 

Now  if  we  suppose  that  the  process  may  be  of  epi- 
genetic  nature,  and  if  we  suppose  also  that  the  different 
anlagen  of  the  germ  substance  becoming  successively  ac- 
tive, are  all  located  in  one  definite  zone  of  the  organism 
from  which  they  send  forth  their  formative  action,  then 
it  is  clear  that  the  different  points  of  the  soma  must 
experience  the  determinative  influence  of  the  paternal  and 
maternal  germinal  anlagen  at  the  same  time. 

Consequently  when  the  corresponding  anlagen  com- 
posing each  couple  are  quite  identical,  as  will  be  the  case 
especially  during  the  first  stages  of  development  and  per- 
haps also  at  subsequent  stages  more  or  less  advanced, 
then  the  two  respective,  determinative  actions  will  be- 
come fused  into  one,  and  there  would  result  the  exact 
reproduction  of  the  entirely  similar  characters  which  the 
two  parents  possess  in  common. 

When  on  the  contrary  the  corresponding  anlagen  com- 
posing each  pair  are  different,  provided  that  they  are  not, 

126Weismann :  Das  Keimplasma.    P.  377. 


156         Explanation  of  P articulate  Inheritance 

we  repeat,  different  to  such  a  degree  that  the  activation 
of  one  prevents  that  of  the  other,  the  two  formative 
actions  will  be  likewise  different  for  all  the  points  of  the 
soma  upon  which  their  action  would  be  perferably  or 
exclusively  directed,  and  they  would  be  able  thus  either  to 
combine  and  thus  unite  into  a  single  resultant  formative 
action,  or,  by  developing  their  respective  characters 
separately,  to  bring  about  an  intimate  interlacing  of 
them,  in  such  a  way  as  to  cause  the  appearance  of  a  com- 
mingled intermediate  character,  or  finally  the  paternal 
character  developed  by  one  of  the  formative  actions  can 
at  a  given  point  prevail  over  the  maternal  to  such  an  ex- 
tent as  to  appear  in  all  its  purity,  while  perhaps  the  reverse 
appears  in  a  neighboring  point  of  the  soma,  and  the 
maternal  character  comes  alone  to  development. 

A  characteristic  example  of  this  interlacement  of  pa- 
ternal and  maternal  characters  remaining  in  part  distinct 
but  in  part  fused,  is  shown  us  by  the  hybrid  arising  from 
the  spontaneous  crossing  of  Vitis  aestivalis  and  Vitis 
labrusca,  the  epidermis  of  whose  leaves  is  formed  like  a 
mosaic,  the  cells  of  which  belong  either  to  the  purely 
paternal  type  or  to  the  purely  maternal  type,  or  to  an 
intermediate  form.126 

If  now  after  considering  the  phenomena  of  particulate 
inheritance  due  to  sexual  reproduction,  we  consider  the 
phenomena  of  this  particulate  inheritance  in  its  broadest 
extent  and  most  general  significance  in  order  to  be  able  to 
answer  the  question ;  how  can  the  simple  fact  be  explained 
that  two  individuals  can  be  altogether  alike  except  for  a 
single  definite  peculiarity  at  a  single  given  point  of  the 

""Strasburger :  t)ber  periodische  Reduktion  der  Chromosomen- 
zahl  im  Entwicklungsgang  der  Organismen.  Biol.  Centralbl.,  Bd., 
XIV.  No.  23  and  24,  Dec.  i.  and  15,  1894.  P.  850. 


Explanation  of  P articulate  Inheritance          157 

organism?  It  will  not  be  difficult  to  convince  us  that  the 
possibility  of  this  phenomenon  will  be  fully  provided  for 
by  the  same  hypothesis  of  the  structure  of  the  germ  sub- 
stance which  has  served  to  explain  for  us  the  same 
phenomenon  in  so  far  as  it  is  due  to  sexual  reproduction. 

Let  us  imagine,  for  example,  two  germinal  substances 
constituted  by  two  series  of  specific  anlagen,  which  are 
qualitatively  alike,  but  in  one  of  which  a  certain  entire 
group  of  these  anlagen  is  furnished  with  a  little  less 
potential  energy  than  in  the  other.  We  do  not  need  to 
suppose,  even  though  we  could,  that  this  certain  group  of 
specific  anlagen  is  of  such  a  nature  that  its  activation  in 
the  above  mentioned  common  zone  from  which  formative 
stimuli  are  given  out  should  determine  preferably  or  exclu- 
sively just  that  part  of  the  organism  which  shows  itself 
capable  of  independent  variation,  such  as  for  example  the 
dimple  in  front  of  the  ear  of  which  Weismann  speaks. 
Instead  we  could  very  well  suppose  that  this  group, 
either  by  itself  or  in  combination  with  others,  brings 
about  definite  ontogenetic  modifications  not  only  in  this 
one  part  but  also  in  many  other  parts,  perhaps  even  in 
all  the  cells  of  the  organism  without  exception.  But 
the  epigenetic  nature  which  we  attribute  to  the  process 
of  development  implies  the  idea  that  the  activation  at 
a  given  stage  of  ontogeny  of  a  definite  specific  anlage 
must  exert  very  different  influences  not  only  qualitatively 
but  quantitatively  upon  the  individual  parts  of  the  soma 
that  are  already  formed.  It  is  thus  conceivable  that 
a  very  small  amount  of  potential  energy  in  a  given 
group  of  specific  germinal  anlagen  might  exert  inappre- 
ciable effects  or  indeed  no  effect  at  all  on  a  definite  or 
even  great  part  of  the  organism,  but  yet  exert  quite  an 
appreciable  or  even  considerable  effect  upon  another  very 


158          Explanation  of  P articulate  Inheritance 

small  part  of  it,  and  so  much  the  more  since  the  effects 
produced  by  this  particular  group  of  germinal  anlagen 
must  combine  with  those  produced  by  all  the  others  both 
antecedent  and  subsequent. 

It  would  amount  to  the  same  thing  if  this  given  group 
of  specific  anlagen  differed  from  the  corresponding  group 
of  the  other  germinal  substance  not  only  quantitatively 
but  also  qualitatively  to  a  certain  extent. 

We  believe  the  final  result  to  be  that  we  can  affirm 
that  the  hypothesis  of  a  heterogeneous  germinal  sub- 
stance whose  anlagen  do  not  all  enter  into  action  from  the 
first  moment  of  development,  but  rather  become  active 
successively  one  by  one,  throughout  the  entire  course  of 
development,  explains  the  phenomena  for  which  pre- 
formistic  germs  were  especially  devised  quite  as  satis- 
factorily as  they  do,  and  at  the  same  time  is  not  open  to 
any  of  the  formidable  objections,  which  demonstate  with 
certainty  the  untenability  of  the  hypothesis  of  pre- 
formistic  germs. 


CHAPTER  FIVE 

THE     QUESTION      OF     THE     INHERITANCE     OF     ACQUIRED 
CHARACTERS 

The  great  service  of  Weismann,  which  is  not  yet 
appreciated  highly  enough,  is  that  he  brought  forward 
this  matter  of  the  inheritance  of  acquired  characters,  and 
questioned  its  existence,  which  previously  had  been  not 
only  tacitly  admitted  by  most  biologists,  but  regarded  as 
not  needing  proof.  And  we  must  recognize  the  fact  that 
the  great  and  justifiable  desire  to  find  for  this  inheritance 
some  proof  which  should  be  irrefutable  and  not  open  to 
any  objections  has  remained  so  far  unfulfilled. 

It  is  not  proposed  here  to  make  a  long  list  of  all  the 
facts  which  have  been  brought  forward  as  proofs  of  the 
Lamarckian  principle,  but  it  will  be  worth  while  to 
examine  a  few  in  order  to  show  clearly  that  Weismann  and 
his  school  are  not  really  far  wrong  in  denying  to  most  of 
these  facts  any  right  to  be  considered  conclusive  proof. 

We  shall  leave  aside  the  question  as  to  whether  calves 
have  really  been  born  without  horns,  as  alleged,  in  con- 
sequence of  the  breaking  off  before  their  conception  of 
the  horns  of  one  or  other  parent;  or  whether  tailless 
calves  were  produced  by  a  bull  whose  tail  had  been 
squeezed  off  at  the  root  by  the  violent  closing  of  the  stable 
door.  It  is  clear  that  all  these  cases  and  many  others  like 
them,  which  have  been  reported  in  dogs,  cats,  rats,  and 


160  Inheritance  of  Acquired  Characters 

so  on,  can  not  constitute  any  satisfactory  proof  in  the 
absence  of  reliable  observation  and  confirmation  of  the 
facts. 

Darwin  draws  especial  attention  to  the  inheritance  of 
characters  acquired  by  domestic  animals.  "The  domes- 
ticated duck,"  he  remarks,  "flies  less  and  walks  more  than 
the  wild  duck  and  the  bones  of  its  anterior  and  posterior 
limbs  have  become  respectively  diminished  and  increased 
in  comparison  with  those  of  the  wild  duck.  A  horse  is 
trained  to  certain  paces  and  the  colt  inherits  similar  con- 
sensual movements.  The  domesticated  rabbit  becomes 
tame  from  close  confinement ;  the  dog  intelligent  from  as- 
sociating with  man;  the  retriever  is  taught  to  fetch  and 
carry;  and  these  mental  endowments  and  bodily  powers 
are  all  inherited."  127 

These  examples,  one  must  admit,  deserve  all  considera- 
tion, especially  the  first.  But  one  encounters  here  the  ob- 
jection which  can  always  be  raised  against  such  examples : 
As  functional  adaptation  has  a  great  modifying  influence 
upon  the  organism,  how  can  we  be  certain  that  the  greater 
size  of  the  bones  of  the  legs  in  the  domestic  duck  really 
springs  from  inheritance  of  acquired  characters  rather 
than  from  the  daily  exercise  of  the  individual  itself? 
Would  not  a  wild  duck  if  it  were  obliged  to  walk  during 
all  its  life  from  its  coming  out  of  the  egg  acquire  a  similar 
hypertrophy  of  these  bones?  Unfortunately  we  have  not 
exact  measurements  on  this  point  which  alone  could  de- 
cide the  question  whether  hypertrophy  acquired  during 
the  life  of  an  individual  could  attain  the  same  degree  as 
that  which  has  been  observed  in  the  domestic  duck. 

Several  travellers  have  remarked  that  when  men  have 

127Darwin :  The  Variation  of  Animals  and  Plants  under  Vol.  II. 
P.  367. 


Apparent  Instances  and  Objections  161 

disembarked  for  the  first  time  upon  uninhabited  islands 
the  animals  have  not  often  any  fear  of  them,  but  after  'a 
very  few  generations  the  fear  of  man  has  become  an 
inborn  instinct. 

Weismann  and  his  followers  could  object  here  also  that 
this  fear  of  man  is  not  even  now  an  inborn  character,  but 
rather  is  simply  acquired  after  birth  and  due  to  the  educa- 
tion, in  the  largest  sense,  which  the  little  animals  con- 
tinually receive  from  their  parents  and  from  all  the  other 
adults  merely  by  observation  and  imitation  of  their  con- 
duct on  definite  occasions. 

"The  co-ordination,  arrangement,  and  connections  of 
the  ganglion  cells  which  innervate  the  muscles  of  speech," 
says  Roux,  "are  already  inborn  in  us  to  such  an  extent 
that  we  learn  to  speak  our  mother  language  easiest,  while 
for  example  Europeans  even  when  brought  among  the 
Namas  while  still  children  never  learn  their  language  as 
perfectly  as  the  Namas  themselves,  or  do  so  only  with 
the  greatest  difficulty."  128 

This  does  not  prevent  any  one  fundamentally  opposed 
to  the  inheritance  of  acquired  characters  from  objecting 
that  the  European  language  spoken  by  the  parents  and 
ancestors  of  the  child  may  not  be  the  cause  of  these  dis- 
positions and  inborn  connections  of  the  ganglion  cells  but 
rather  the  effect ;  in  other  words,  it  is  not  the  use  of  this 
or  that  speech  which  develops  such  and  such  inheritable 
connections;  but  rather  the  presence  of  certain  connec- 
tions due  to  natural  selection  has  produced  certain 
peculiarities  in  the  character  of  the  language  of  a  given 
human  race. 

"When  young  hunting  dogs,"  writes  Exner,  "which 

128Roux:  Der  Kampf  der  Teile  im  Organismus.    P.  38. 


162  Inheritance  of  Acquired  Characters 

have  never  been  out  hunting,  nor  had  occasion  to  become 
otherwise  acquainted  with  guns  and  their  effects,  hear  one 
in  the  fields  for  the  first  time  they  start  up  eagerly,  just 
like  old  hunting  dogs,  to  retrieve  the  prey  even  when 
they  do  not  see  any  fall.  This  demonstrates  that  since  the 
invention  of  gunpowder  the  mnemonic  image  of  a  gun- 
shot and  its  effects  has  passed  hereditarily  into  the  brain 
of  the  dog,  and  so  has  been  gathered  up  in  the  so  called 
instinct."  129 

And  here,  we  do  not  really  know  what  objection  the 
Neo-Darwinians  could  bring  forward ;  for  it  seems  to  us 
that  they  would  encounter  difficulties  in  trying  to  attribute 
the  formation  of  this  instinct  in  a  brain  which  was  abso- 
lutely tabula  rasa  in  so  far  as  this  instinct  is  concerned,  to 
the  artificial  selection  of  the  breeders.  We  must  never- 
theless recognize  that  even  this  example  does  not  fulfill, 
and  cannot  from  the  nature  of  it  fulfill  all  the  requisite 
conditions  of  exact  observation,  of  measurement,  of  con- 
trol, and  particularly  of  comparison  which  alone  could 
give  a  single  case  the  value  of  a  decisive  proof. 

A  very  remarkable  example  is  reported  by  LeDantec. 
The  shells  of  Hyatt's  oldest  cephalopods  have  the  form  of 
a  cows  horn  nearly  circular  in  transverse  section.  And 
following  the  series  of  these  fossils  in  the  more  recent 
strata,  one  notes  that  these  shells,  at  first  almost  straight, 
are  little  by  .little  rolled  up  upon  themselves  like  an  Arch- 
imedes' spiral.  The  presence  of  certain  characters  shows 
clearly  that  the  rolled  up  forms  are  descended  from  those 
with  the  straight  shell.  In  a  few  types  the  rolling  up  is  so 
marked  that  the  successive  turns  of  the  spiral  press  one 

129Exner:  Physiologic  der  Gro^hirnrinde,  in  Hermann:  Hand- 
buch  der  Physiologic.  Zw.  Bd.,  Zw.  Teil.  Leipzig,  Vogel,  1879. 
P.  282—283. 


Apparent  Instances  and  Objections  163 

into  another,  giving  rise  to  a  dorsal  groove  the  mechanical 
production  of  which  is  evident  since  it  undoubtedly  re- 
sults from  the  pressure  of  the  preceding  spiral  upon  the 
succeeding.  Now  in  a  still  more  recent  geological  period 
paleontological  discoveries  show  that  the  descendants  of 
these  cephalopods  with  a  tightly  rolled  up  shell  have  begun 
to  unroll,  and  have  then  the  form  of  an  Archimedes, 
spiral  with  broader  turns  which  no  longer  touch  one 
another.  But  the  dorsal  groove  persists  even  in  these  half 
rolled  up  shells,  a  proof  that  the  younger  cephalopods 
have  repeated  hereditarily  this  character  which  was 
acquired  by  their  ancestors.130 

This  is  certainly  a  most  interesting  example,  but  it 
has  not  quite  the  force  of  complete  proof.  For  besides 
the  objection,  which  we  shall  examine  later,  that  the 
groove  is  formed  in  the  non-living  substance  of  the  shell, 
it  does  not  exclude  the  interpretation,  though  it  be  only 
verbal  and  without  any  real  foundation,  that  it  was  not 
the  rolling  up  of  the  spiral  upon  itself  that  produced  the 
inherited  groove,  but  rather  that  both  the  tight  rolling 
up  and  the  groove  were  selected  and  fixed  independently 
of  one  another  by  natural  selection. 

The  influence  of  dry,  hot  climates  upon  the  develop- 
ment of  the  horns  of  cattle  and  sheep  is  well  known.  If 
certain  individuals  of  a  certain  breed  of  cattle  are  trans- 
ported from  a  wet,  cold  climate  to  a  hot  dry  climate,  the 
horns  increase  in  length  and  circumference  and  the  skin 
thickens.  The  following  fact  seems  to  prove  that  this 
acquired  elongation  of  the  horns  is  inheritable.  A  cow 
was  transported  from  Algau  in  Bavaria  where  the  climate 
is  moist  and  cold,  into  the  dryer  and  hotter  steppes  of 

180Le  Dantec :  Traite  de  Biologic.    P.  296—297. 


164  Inheritance  of  Acquired  Characters 

Hungary.  This  cow  whose  horns  were  19  cm.  long  gave 
birth  to  a  calf  with  horns  22  cm.  long.  The  calf  of  this 
calf  born  also  in  Hungary,  (presumably  from  a  father 
of  the  same  race  as  that  of  the  mother?)  had  horns  23 
cm.  long  and  thicker  than  those  of  its  mother  and  grand- 
mother.131 

So  of  the  three  centimeters  of  elongation,  due  to  the 
action  of  the  environment,  which  we  can  regard  as 
functional  adaptation  in  the  widest  sense,  one  centimeter 
would  have  become  hereditary  in  a  single  generation.  It 
is  however  evident  that  experiments  of  this  nature  can- 
not have  any  real  significance  unless  they  are  made  on 
a  large  scale,  so  that  an  average  can  be  established  from 
many  instances.  And  this  experiment  of  Wilckens  has 
been  mentioned  here  just  because  the  way  in  which  it 
was  conducted  comes  close  to  possessing  the  requisite 
and  indispensable  conditions  of  a  fundamental  proof. 

Another  instance  which  the  partisans  of  the  inherita- 
bility  of  acquired  characters  adduce  is  brought  forward 
by  Spencer:  it  is  that  of  the  Punjabi  of  India,  who  have 
certain  muscle  imprints  on  the  bones  of  the  leg,  and 
certain  facets  in  the  articulations  of  the  hip,  knee  and 
foot,  which  are  produced  by  their  habit  of  squatting  upon 
the  ground;  and  these  peculiarities  are  hereditary,  as  is 
demonstrated  by  the  fact  that  they  commence  to  show 
themselves  even  in  the  foetus. 

Weismann  seeks  to  demonstrate  that  they  are  only 
the  continuation  in  man  of  certain  peculiarities  in  the 
articulations  of  anthropoid  apes  which  natural  selection 
had  already  fixed  in  very  ancient  times  because  they 

191Wilckens :  Die  Theorie  erworbener  Eigenschaften  vom  Stand- 
punkte  der  landwirtschaftlichen  Tierzucht  in  Bezug  auf  Weismanns 
Theorie  der  Vererbung.  Biol.  Zentralbl.,  July  15,  1893.  P.  426. 


Apparent  Instances  and  Objections  165 

were  useful  then.  But  still,  in  our  opinion,  he  has  not 
been  able  to  explain  correctly  why  these  peculiarities  are 
retained  only  in  the  Punjabi,  who  are  also  the  only  ones 
of  all  the  tribes  of  the  same  family  who  are  accustomed 
to  squat  in  this  way.132 

One  could  bring  up  also  as  examples  the  callosities 
at  the  knees  and  sternum  which  are  hereditary  in  the 
domestic  camels  but  are  lacking  in  the  wild  camels.  Thus 
for  example  the  camels  of  the  tame  stock  of  San  Rossore 
near  Pisa  (Italy)  are  covered  with  hair  both  over  the 
breast  bone  and  on  the  knee  at  birth,  but  after  a  few 
days  they  lose  the  hair  in  the  breast  bone  region,  which 
is  then  permanently  replaced  by  a  horny  plate.  Every 
camel  up  to  three  months  old  had  these  more  or  less 
broad,  hairless  plates,  though  they  still  retained  the  hair 
on  the  knee,  but  the  thickened  and  hardened  skin  could 
be  felt  under  it.  Of  course  these  camels  which  were 
only  a  few  months  old  were  not  required  to  do  any 
work.  On  wild  camels,  on  the  contrary,  no  such  swellings 
are  to  be  found  either  in  the  very  young  or  the  adult.133 

Still  more  remarkable  is  the  following  fact  reported 
in  1888  by  Prof.  Fogliata.  "A  she  ass  from  the  Tuscan 
Appenines,  which  long  had  borne  the  pack  saddle,  showed 
on  the  back  and  on  both  sides  over  the  ribs,  a  very 
evident  pad  of  soft  fat,  which  in  extent  and  shape  was 
like  those  which  the  pressure  of  an  ordinary  mountain 
pack  saddle  produces.  This  she  ass  was  put  to  an  ordi- 

t82Weismann :  Neue  Gedanken  zur  Vererbungsfrage.  Eine  Ant- 
wort  an  Herbert  Spencer.  Jena,  Fischer,  1895.  P.  54ff. 

183Cattaneo :  Le  gobbe  e  le  callosita  dei  cammelli  in  rapporto  colla 
questione  della  ereditarieta  dei  caratteri  acquisiti.  Estratto  dai  Ren- 
diconti  del  R.  Istituto  Lombardo  di  sc.  e  lettere.  Serie  II,  Bd.  XXIX, 
1896.  P.  10 — ii ;  and:  I  fattori  della  Evoluzione  Biologica.  Genua, 
Martini,  1897.  P.  40 — 41. 


1 66  Inheritance  of  Acquired  Characters 

nary  male  ass  and  bore  a  female  colt  which  shows  the 
same  peculiarity  as  the  mother.  Its  fat  pad  which  covers 
the  back  and  reaches  almost  half  way  down  the  ribs  is 
not  less  than  5  cm.  thick,  clearly  defined,  and  has  an 
abrupt  and  perpendicular  margin.  It  is  to  some  extent 
a  distinct  and  separate  fat  mass, — a  true  lipoma, — cer- 
tainly similar  to  those  which  according  to  Lombroso's 
description  are  produced  by  burden  bearing.  It  has  the 
same  character  as  the  hump  of  the  camel,  is  more  or  less 
developed  according  to  the  condition  of  nutrition  of  the 
animal,  and  appears  exactly  as  though  it  had  arisen  by 
the  pressure  exerted  by  a  saddle  on  the  back.  Also  the 
hair  is  longer  and  thicker  over  the  whole  of  the  fat  layer, 
which  agrees  likewise  with  the  observations  of  Lom- 
broso  on  pack  animals  possessing  such  lipomas,  and  is 
like  the  hump  of  camels  also,  which  is  covered  with 
thicker,  longer  wool.  It  is  worthy  of  remark  that  this 
young  she  ass  has  never  borne  a  saddle  and  inherits  its 
peculiarity  entirely  from  the  mother,  which  proves  be- 
yond doubt,  that  this  peculiarity,  acquired  by  pressure 
on  the  back,  has  been  inherited.134 

Even  though  this  single  fact  cannot  decide  the  ques- 
tion finally  we  do  not  really  see  what  objection  Weismann 
and  his  school  could  urge  against  it. 

Finally  we  have  the  celebrated  experiments  of  Brown 
Sequard  on  guinea  pigs,  proving  the  transmissibility  to 
the  young  of  effects  produced  in  the  parents  by  certain 
accidental  lesions. 

Thus  he  has  demonstrated  that  epilepsy,  produced  in 
one  of  the  parents  by  section  of  the  sciatic  nerve  or  of  a 
part  of  the  spinal  cord,  is  transmissible  to  the  young. 

18*Cattaneo:  Le  gobbe  e  le  callosita  dei  cammelli  etc.    P.  9 — 10. 


Instances  Reported  by  Brown  Sequard          167 

After  section  of  the  sympathetic  trunk  in  the  neck 
there  was  produced  a  particular  change  in  the  form  of 
the  ear  or  a  partial  closing  of  the  eyelids,  and  the  same 
modification  of  the  ear,  and  the  same  closure  of  the 
eyelid  were  reported  in  their  respective  descendants. 

A  lesion  of  the  medulla  oblongata  produced  exophthal- 
mos  in  certain  guinea  pigs  and  the  same  exophthalmos 
showed  itself  in  the  young. 

Ecchymoses  accompanied  by  dry  gangrene  and  other 
alterations  of  the  nutrition  of  the  ear  have  been  reported 
in  the  descendants  of  individuals  in  which  this  series  of 
phenomena  had  been  produced  by  a  lesion  of  the  restiform 
body. 

Certain  other  guinea  pigs  in  which  section  of  the 
sciatic  nerve  had  rendered  the  hind  foot  insensible  to 
pain  gradually  destroyed  their  toes  by  gnawing  them; 
it  is  reported  that  in  their  descendants  parts  of  the  toes 
or  even  whole  toes  were  missing  from  one  of  the  hind 
feet. 

Other  individuals  in  which  the  sciatic  nerve  had  been 
cut  had  descendants  which  exhibited  at  first  a  diseased 
condition  of  the  same  sciatic  nerve,  and  later  the  phe- 
nomena characteristic  of  the  onset  and  decline  of  epilepsy, 
particularly  the  development  of  an  epileptogenous  capac- 
ity in  a  zone  of  skin  of  the  head  and  neck,  and  a  loss  of 
hair  toward  the  decline  of  the  affection. 

Guinea  pigs  which  had  had  an  eye  altered  in  conse- 
quence of  the  transverse  section  of  the  restiform  body 
had  descendants  which  all  showed  more  or  less  imperfec- 
tion in  one  or  both  of  the  two  eyes. 

In  more  than  a  score  of  guinea  pigs  representing 
the  total  posterity  of  individuals  in  which  muscular 
atrophy  had  developed  after  section  of  the  sciatic  nerve 


1 68  Inheritance  of  Acquired  Characters 

there  appeared  just  such  a  muscular  atrophy  of  the  thigh 
and  of  the  leg.135 

The  desperate  endeavor  which  Weismann  has  made 
to  refute  the  results  of  these  experiments,  at  least  in 
relation  to  the  transmissibility  of  epilepsy,  is  well  known, 
objecting  that  this  affection  was  due  only  to  an  infection 
innoculated  in  the  parents  after  operation  and  so  trans- 
mitted to  the  germ.  Brown  Sequard  has  signally  over- 
come this  objection  by  showing  that  epilepsy  is  not 
produced  by  all  nerve  sections  but  only  by  some,  and 
that  further  it  can  be  provoked  also  by  the  simple  crush- 
ing of  the  sciatic  nerve  without  any  breaking  of  the  skin, 
and  this  would  exclude  the  possibility  of  any  infection 
whatever. 

Nevertheless  it  is  necessary  to  recognize  the  fact  that 
these  experiments,  while  they  undoubtedly  demonstrate 
the  inheritance  of  the  effects  of  certain  lesions,  are  not 
enough  to  produce  a  firm  and  general  conviction  of  the 
inheritance  of  acquired  characters  among  the  numerous 
naturalists  and  biologists  who  are  in  no  wise  blind  fol- 
lowers of  Weismann's  theories;  perhaps  because  what 
is  inherited  in  these  cases  is  always  somewhat  morbid 
and  abnormal.  In  short  the  determination  of  the  ques- 
tion requires  certain  proof  of  the  inheritance  of  definite 
normal  peculiarities  acquired  by  functional  adaptation. 

We  see  then,  that  whoever  proposes  systematically 
to  hunt  out  a  weak  point  in  every  fact  adduced  in  support 
of  the  Lemarckian  principle,  by  which  its  value  as  proof 
can  be  shaken,  can  usually  if  not  always  find  it.  But 

138Brown  Sequard:  Faits  nouveaux  etablissant  Textreme  fre- 
quence de  la  transmission,  par  heredite,  d'etats  organiques  morbides, 
produits  accidentellement  chez  des  ascendants.  Comptes  Rendus  de 
1'Acad.  der  Sciences.  T.  XCIV,  No.  n,  March  13,  1882.  P.  697—700. 


The  Non-inheritance  of  Amputations  169 

this  would  justify  the  assertion  that  the  inheritance  of 
acquired  characters  has  not  yet  been  directly  proven,  only 
in  the  case  that  there  were  but  a  few  facts  or  only  a 
single  fact  that  could  be  brought  forward  in  proof  of 
it.  But  when  on  the  contrary  there  are  a  very  large 
number  of  facts  favorable  to  a  given  principle,  even 
though  each  one  of  them  by  itself  would  not  be  an 
absolutely  incontestable  proof,  they  would  in  spite  of 
that  have,  when  taken  as  a  whole,  a  very  great  value 
as  proof,  and  this  value  would  be  so  much  the  greater 
if  the  opponents  of  the  principle,  in  seeking  to  deny  the 
incontestability  of  the  individual  facts,  are  forced  to 
resort  to  as  many  specially  devised  subtleties. 

On  the  other  hand  the  non-inheritance  of  certain 
gross  instantaneous  modifications,  such  as  amputations 
and  other  similar  things,  of  which  Weismann  and  his 
followers  make  so  great  a  case,  proves  nothing  against 
the  inheritance  of  functional  adaptations  which  are  of  quite 
different  nature. 

For  let  us  consider  the  dynamic  equilibrium  existing 
in  the  adult  state  in  a  given  small  portion  of  the  soma, 
and  let  us  suppose  also  that  this  equilibrium  was  estab- 
lished by  a  process  of  epigenetic  nature  dependent  upon 
all  the  rest  of  the  organism.  If  this  local  equilibrium 
is  suddenly  very  much  disturbed  as  is  the  case  in 
amputations,  instead  of  gradually  and  slowly  as  in 
functional  adaptations,  one  can  understand  that  it  can 
and  must  be  promptly  restored  in  the  neighborhood 
of  the  wound  or  in  any  case  in  the  limited  area  of 
the  stump,  before  the  disturbance  has  time  to  extend 
much  farther.  Therefore  if  there  is  a  definite  place 
in  the  organism  to  which  non-transitory  derangements 
and  the  variations  of  equilibrium  caused  thereby  must 


170  Inheritance  of  Acquired  Characters 

penetrate  if  the  corresponding  morphological  modification 
is  to  be  inheritable,  it  follows  that  amputations,  unlike 
functional  adaptations,  could  not  as  a  rule  leave  any 
trace  of  themselves  in  the  descendants. 

But  in  still  another  very  essential  point  amputations 
are  different  from  functional  adaptation.  The  ampu- 
tation of  a  limb,  or  of  a  piece  of  a  tail,  does  not  con- 
stitute in  any  way  the  mode  of  reaction  of  the  organism 
to  a  definite  external  influence,  but  rather  it  is  this 
external  influence  itself.  How  then  will  its  reproduction 
in  the  new  organism  be  possible?  This  would  be  the 
same  thing  as  expecting  that  an  individual  who  had 
been  accustomed  throughout  his  life  to  bear  a  burden 
upon  his  shoulders  as  exercise,  should  transmit  to  his 
son  not  only  stronger  bones  and  muscles  but  also  the 
burden  itself  which  was  the  cause  of  this  strengthening. 

So  that  the  most  that  could  be  transmitted  to  the 
descendants  of  an  animal  \vhich  had  undergone  some 
amputation,  would  be  the  mode  of  reaction  of  the  organ- 
ism to  this  gross  external  influence,  that  is  all  the  phe- 
nomena constituting  the  cicatrization,  properly  so  called, 
of  the  wound,  as  wrell  as  the  establishment  of  a  new  local 
equilibrium.  We  must  however  bear  in  mind  in  this 
connection  that  the  reproduction  in  the  child  of  con- 
siderably thicker  and  stronger  bones  and  muscles  will 
not  be  hindered  by  the  fact  that  it  is  not  exposed  to  the 
same  external  influence  which  acted  upon  the  parent, 
i.  e.  by  the  fact  that  it  does  not  bear  the  same  burden 
as  its  father,  but  that  if  one  does  not  also  repeat  the 
amputation,  the  repetition  of  all  the  phenomena  con- 
stituting the  cicatrization  of  the  wound  and  the  reestab- 
lishment  of  a  new  equilibrium  could  not  but  be  very 
much  hindered  and  usually  quite  prevented  by  the  pres- 


The  Decisive  Experiment  171 

ence  of  the  limb  or  other  part  of  the  body  which  was 
destroyed  in  the  parent. 

In  order  to  make  this  more  apparent  let  us  con- 
sider some  one  of  the  numerous  rats  from  which 
Weismann  cut  off  the  tails,  and  which  that  author  has 
rightly  brought  forward  as  proving  that  the  surgical 
operation  of  amputation  is  not  inherited.  Let  us  sup- 
pose that  in  the  young  rat  when  once  his  development 
was  completed  and  he  had  arrived  at  about  the  age  at 
which  the  old  rat  had  undergone  the  amputation,  really 
showed  at  the  spot  at  which  the  amputation  took  place 
a  tendency  to  reproduce  the  same  phenomena  of  cicatri- 
zation and  reestablishment  of  the  new  local  equilibrium 
which  had  supervened  in  the  parent.  It  is  evident  that 
the  absence  of  the  tail  is  a  necessary  condition  in  order 
to  make  the  reproduction  of  these  phenomena  materially 
possible.  This  tendency  must  then  be  hindered  and  per- 
haps absolutely  suppressed  so  long  as  the  tail  remains  a 
part  of  the  organism. 

It  is  interesting  in  this  connection  to  note  that  Kohl- 
wey  has  obtained  in  one  and  the  same  individual  a  com- 
pletely negative  result  in  respect  to  the  inheritance  of 
mutilations,  but  a  positive  result  in  respect  to  the  trans- 
mission of  habit:  He  cut  off  the  posterior  digit  from 
the  feet  of  some  pigeons  which  thereupon  turned  back 
another  digit  in  order  to  retain  their  perch;  and  in  one 
instance  this  habit  was  reproduced.136 

The  decisive  experiment  upon  the  inheritance  of  ac- 
quired characters  must  leave  amputations  and  similar 
sudden  variations  out  of  consideration,  since  either  their 
effect  is  to  bring  about  the  reestablishment  of  an  exclu- 

L86H.  Kohlwey:  Arten  und  Rassenbildung.  Eine  Einfiihrung  in 
das  Gebiet  der  Tierzucht.  Leipzig,  Engelmann,  1897,  P.  6 — 7. 


172  Inheritance  of  Acquired  Characters 

sively  local  equilibrium  or  the  repetition  in  the 
descendants  of  the  phenomena  by  which  the  parent 
organism  reacted  is  hindered.  This  experiment  must 
rather  be  directed  toward  modifications  of  the  functional 
adaptation,  wihch  have  a  very  extensive  action  and  whose 
repetition  in  the  descendants  is  not  hindered  by  anything. 

In  order  that  these  experiments  on  the  changes 
dependent  upon  functional  adaptation  may  constitute  an 
incontestable  proof  for  or  against  the  inheritance  of 
acquired  characters, — which  latter  are  to  be  understood 
in  Weismann's  sense  as  only  somatic  and  not  general 
peculiarities  of  the  entire  organism, — they  must  be 
planned  in  such  a  way  as  to  make  it  certain  that  the 
change  effected  by  the  transforming  influence  has  affected 
only  the  soma  directly,  and  for  still  greater  certainty  it 
ought  to  act  upon  only  a  definite  part  of  the  soma 
and  not  upon  the  entire  soma  to  the  same  extent.  They 
must  also  be  undertaken  on  pluricellular  organisms  in 
which  the  somatic  germ  cells  are  clearly  differentiated, 
and  there  ought  to  be  employed  as  transforming  influ- 
ences only  such  as  certainly  exert  no  direct  influence  upon 
the  reproductive  cells.137 

All  plants  in  which  the  difference  between  somatic 
and  germ  cells  is  not  a  thorough  going  and  definite  one 
will  therefore  be  less  suitable  for  these  researches  than 
animals,  and  particularly  higher  animals,  and  all  such 
investigations  both  in  animals  and  in  plants  which  em- 
ploy physical  or  chemical  transforming  agents  exerting 
a  general  action  on  the  entire  organism,  on  the  somatic 
cells  as  well  as  on  the  germ  cells,  as  for  example  tem- 

187Compare  J.  De  Meyer:  L'heredite  des  caracteres  acquis  est- 
elle  experimentalement  verifiable?  Archives  de  Biologic.  Tome  XXI, 
No.  Ill  and  IV.  Paris,  Masson  1905,  P.  625,  634 — 639. 


The  Decisive  Experiment  173 

perature,  light  or  darkness,  particular  substances  that  are 
nutritive,  stimulating  or  poisonous,  infections,  immuniza- 
tions, etc.,  could  never  afford  such  incontestable  evidence 
against  Weismann's  theory,  as  those  investigations  which 
employ  agents  having  a  very  definitely  localized  action. 

Thus  for  example  Heschenhagen's  researches  upon 
the  adaptability  of  the  lower  fungi  to  sodium  chloride 
have,  for  the  reasons  stated,  little  or  no  value  for  the 
refutation  of  Weismann's  theory,  even  though  they  have 
proved  that  the  spores  of  the  mycelium  which  had 
adapted  itself  to  a  strongly  concentrated  saline  solution 
were  capable  of  germinating  in  concentrations  in  which 
the  spores  of  a  mycelium  arising  in  normal  conditions 
were  incapable  of  germinating.  The  same  is  true  for 
the  similar  researches  carried  on  by  Hunger-Errera, 
DeMeyer,  Pulst  and  Ray  upon  the  inheritance  of  changes, 
mostly  physiological  rather  than  morphological  in  nature, 
which  were  brought  about  in  the  lower  fungi  by  means 
of  concentrated  salt  solutions,  for  example  by  sodium 
chloride  or  copper  sulphate  or  concentrated  sugar  solu- 
tions, although  these  results  as  well  as  Heschenhagen's 
are  certainly  very  interesting  from  the  point  of  view  of 
the  adaptability  of  organisms  to  their  environment. 

Also  Hoffman's  researches  upon  the  inheritance  of 
variations  produced  by  insufficient  nourishment  in 
Papaver,  Migella,  and  Argemone, — (a  relatively  large 
number  of  atypical  flowers), —  and  Schubeler's  researches 
upon  the  inheritance  of  the  more  rapid  development  of 
barley  grains  which  had  been  transplanted  from  the  south 
part  of  Norway  to  the  north  part,  prove  incontrovertibly 
the  inheritance  of  the  changes  induced  in  organisms 
through  general  conditions  in  their  environment,  but  the 
general  influences  very  probably  exerted  in  those  cases  also 


174  Inheritance  of  Acquired  Characters 

by  the  selected  transforming  agent  upon  the  whole  organ- 
ism, and  our  entire  ignorance  of  the  real  nature  of  its 
peculiar  action,  deprive  these  experiments  of  any  value 
as  arguments  against  the  theory  of  Weismann  which 
denies  the  inheritance  of  any  peculiarly  somatic  char- 
acters that  have  been  acquired  by  means  of  local  func- 
tional adaptation  to  external  influences  that  are  very 
definitely  and  clearly  limited. 

Just  as  little  valuable  as  proof  against  Weismann's 
theories  were  the  researches  of  Standfuss,  Fischer,  and 
Bachmetjeff  on  the  inheritance  of  changes  in  the  color 
design  of  butterflies'  wings,  when  the  pupae  concerned 
were  placed  in  an  unusually  high  or  low  temperature, 
so  that  Weismann,  as  we  shall  see  further  in  the  next 
chapter,  could  acknowledge  the  otherwise  unimpeachable 
results  of  these  researches  without  thereby  being  com- 
pelled to  retrench  his  own  theory. 

It  would  be  best  therefore  to  employ  mechanical 
means,  and  to  produce  changes  whose  mode  and  place 
of  working  can  be  easily  observed  and  definitely  limited. 
But  amputations  are  to  be  excluded  for  the  reasons 
given,  as  are  also  sudden  transformations,  and  so  there 
remains  as  the  experiments  best  adapted  for  the  final 
decision  of  this  disputed  question,  prolongation  or  fre- 
quent repetition  of  the  activity  of  certain  organs  or 
definite  parts  of  organs. 

We  might  suggest  for  example  the  artificial  and 
therefore  extraordinarily  frequent  extension  or  contrac- 
tion of  the  muscles  of  the  fore  or  hind  legs  of  a  certain 
animal,  such  as  could  be  effected  in  little  amphibia  or 
little  mammals  with  the  help  of  an  especially  devised 
clock  work.  Prolonged  traction  on  the  tail  of  the  rat 
leading  to  its  elongation  and  growth  should  be  substituted 


The  Decisive  Experiment  175 

for  Weismann's  amputation  which  can  prove  nothing. 
Similarly  light  hammering,  continually  repeated,  which 
a  proper  mechanism  might  automatically  perform  upon 
certain  parts  of  the  skull  of  hornless  animals,  would  be 
better  than  cutting  off  or  breaking  the  horns  in  horned 
animals. 

All  these  artificial  stimuli  would  certainly  produce  in 
each  individual  the  hypertrophy  of  the  organ  upon  which 
they  act.  It  could  then  be  seen  whether  the  repetition  of 
these  stimuli  throughout  a  series  of  generations  would  be 
followed  by  the  production  of  individuals  in  which  these 
organs  would  possess  at  birth  even  in  a  small  proportion 
the  greater  development  that  had  been  acquired  in  several 
successive  generations  of  its  ancestors.  The  performance 
of  such  experiments  upon  guinea  pigs  or  rats  would  not 
seem  to  present  very  great  practical  difficulties;  never- 
theless, so  far  as  we  know,  it  has  never  yet  occurred  to 
any  one  to  make  them  or  to  propose  them. 

But  in  all  these  experiments  one  must  never  forget 
that  it  is  just  the  littleness  of  the  inheritable  fraction  of 
an  acquired  quantitative  variation,  that  constitutes  the 
great  difficulty  of  verification  of  the  Lamarckian  principle. 

Galton  proposes  as  is  known  to  select  for  experi- 
ment rather  the  inheritance  or  non-inheritance  of  certain 
acquired  instincts.  He  advises  for  example  to  adopt  the 
method  of  the  following  experiment  of  Mobius  upon  the 
pike;  Mobius  divided  a  large  glass  receptacle  into  two 
compartments  by  means  of  a  perfectly  transparent  glass 
septum  and  placed  the  pike  in  one  compartment  and  in 
the  other  little  gudgeons  upon  which  the  pike  usually 
feeds.  It  followed  that  whenever  the  pike  precipitated 
himself  toward  any  of  the  little  fishes  he  was  stopped  by 
the  glass  against  which  he  hit.  After  several  weeks  of 


176  Inheritance  of  Acquired  Characters 

useless  attempts  the  pike  finally  gave  up  any  attempt 
to  catch  this  unseizable  prey  and  he  persisted  in  this  atti- 
tude even  after  the  glass  had  been  removed.  Now  Galton 
advises  repeating  this  same  experiment  on  several  genera- 
tions of  pikes,  taking  care  that  each  generation  should 
always  be  brought  up  apart  from  the  preceding  to  prevent 
any  possibility  of  the  educative  influence  of  imitation, 
and  seeing  if  one  would  finally  obtain  any  descendant 
in  which  the  instinct  to  throw  himself  upon  the  gudgeons 
would  be  replaced  by  the  contrary  instinct  of  indifference 
toward  them.138 

We  should  remark  in  this  connection  that  because 
one  is  here  concerned  with  establishing  the  transmission 
of  an  acquired  instinct  that  is  opposed  to  the  inborn 
instinct,  experiments  of  this  nature  are  less  advisable 
than  those  which  seek  rather  to  verify  the  inheritance 
of  a  simple  quantitative  increase  acquired  by  already 
existing  organs  or  tendencies.  In  Galton's  experiment 
the  tendency  of  the  descendants  to  produce  the  new  in- 
stinct even  if  it  were  present  through  a  long  series  of 
generations,  might  not  possess  sufficient  potential  energy 
to  enable  it  to  manifest  itself  through  activation  because 
it  would  have  to  overcome  a  pre-existing  tendency  which 
in  the  beginning  at  any  rate  is  certainly  furnished  with 
a  greater  quantity  of  potential  energy.  Therefore  it  is 
probable  that  it  would  be  necessary  to  submit  a  very  long 
series  of  generations  to  this  experiment  of  the  glass  par- 
tition before  the  new  tendency  would  be  able  to  attain 
a  superiority  over  the  former  and  to  replace  it.  The 
first  pike  upon  which  Mobius  made  his  experiment 

138Galton :  Feasible  Experiments  on  the  Possibility  of  transmit- 
ting acquired  Habits  by  Means  of  Inheritance.  Paper  read  at  the 
British  Association.  Nature,  October  17,  1889.  P.  610. 


Weismann's  Arguments  Against  Inheritance      177 

furnishes  us  itself  a  proof  of  this.  For  from  the  first 
impact  against  the  glass  partition  the  inclination  con- 
trary to  its  instinct  must  have  commenced  to  arise; 
nevertheless  it  effected  the  replacement  of  the  latter 
only  after  a  large  number  of  unavailing  attempts. 

From  all  that  we  have  said  thus  far  it  follows  that 
it  is  much  to  be  desired  that  new  and  absolutely  incon- 
testable experiments  should  once  for  all  finally  place  the 
inheritance  of  acquired  characters  beyond  a  doubt.  But 
it  also  follows,  as  we  have  said,  that  if  no  one  of  the 
proofs  which  we  possess  already  demonstrates  this  in- 
heritance in  an  absolutely  certain  way,  nevertheless  all 
together  they  supply  a  great  weight  of  evidence  for  it. 
As  we  shall  see  later  this  is  true  also  of  indirect  proofs; 
one  cannot  say  of  any  one  of  them  that  it  decides  the 
question  in  one  way  or  the  other,  but  all  together 
they  constitute  a  strong  presumption  in  favor  of  the 
Lamarckian  theory. 

It  will  be  convenient  to  examine  next  the  chief  argu- 
ments which  Weismann  has  adduced  against  this  theory. 
They  can  be  reduced  in  substance  to  the  following: 

i.  "In  many  animals,"  he  writes,  "for  instance  in 
many  insects,  instincts  appear  which  are  exercised  only 
once  during  life.  It  is  sufficient  to  cite  the  laying  of 
eggs  by  ephemerids  and  many  butterflies,  the  conjugation 
of  bees,  the  search  for  proper  hiding  places  in  which 
caterpillars  may  change  into  chrysalids, — one  species 
suspends  itself,  another  lying  on  the  ground  builds  de- 
fences, a  third  goes  deep  into  the  earth,  a  fourth  spins 
itself  a  case  in  a  rolled  up  leaf,  and  so  on,  and  so  on. 
Further  there  belong  here  the  several  species  of  cocoons 
which  some  butterflies,  especially  the  bombycids,  spin 
in  a  fashion  so  astonishingly  complicated  and  so  well 


178  Inheritance  of  Acquired  Characters 

adapted  to  its  purpose,  a  thing  which  each  individual  does 
only  once  and  from  the  most  ancient  times  has  done 
only  a  single  time  in  all  its  life."  139 

2.  The    second    group    of    facts    controverting    the 
inheritance  of  acquired  characters  is  furnished,  accord- 
ing to  Weismann,  by  the  parts  which  have  only  a  passive 
function,  "in  so  far  as  they  show  that  they  also  become 
rudimentary  and  finally   disappear  if  they  cease  to  be 
used  and  are  not  necessary  for  the  preservation  of  the 
species.     They  show  that  the  process  of  disappearance 
which  the  Lamarckians  attribute  to  the  inheritance  of 
the  direct  effects  of  non-usage  cannot  be  due  to  this 
cause,  since  here  the  organ  in  question  does  not  exert 
any  physiological   function  and  so  there  are  of  course 
no  effects  of  such  function  in  the  individual  life.     To 
this  category  belong  for  example  the  colors  of  animals, 
which  become  unstable  when  they  are  no  longer  needed 
for  protection  or  as  a  means  of  recognition;  here  also 
belongs   the   deterioration    of    the    chitinous   cuirass    of 
various  crustaceans   and   insects  which   thrust  one  part 
of  their  body  into  protective  envelopes."  14° 

3.  The  third  argument  against   the   inheritance  of 
acquired   characters   is   that  constituted   by   the   neutral 
individuals  among  bees,  ants,  and  termites  which,  accord- 
ing to  Weismann,  show  that  all  the  adaptations  whether 
positive  or  negative,  isolated  or  co-ordinated,  that  are  to 
be  observed  in  propagating  individuals,  appear  also  in 
individuals  which  do  not  propagate    at    all    and    which 
therefore  do  not  transmit  anything.141 

"'Weismann :  Neue  Gedanken  zur  Vererbungsfrage.    Eine  Ant- 
wort  an  Herbert  Spencer.     P.  61 — 62. 
140Weismann :  Ibid.    P.  62—63. 
141  Weismann:  Ibid.   P.  66. 


Consideration  of  Weismanris  Arguments        179 

4.  Finally  the  last  argument  of  Weismann  is  that 
it  is  incomprehensible  how  the  inheritance  of  acquired 
characters  could  be  effected.142 

In  the  endeavor  to  examine  these  four  arguments 
with  the  most  scrupulous  objectivity,  we  must  first  divide 
them  into  two  categories:  The  fourth  is  the  only  one 
which  attacks  the  principle  of  inheritance  directly;  the 
first,  the  second,  and  the  third,  on  the  contrary,  con- 
trovert this  theory  only  indirectly,  in  that  they  seek  to 
show  that  many  formations  are  of  such  a  nature  or 
arose  under  such  circumstances  that  they  can  be  explained 
only  by  the  theory  of  natural  selection.  The  conclusion 
which  it  is  desired  to  have  drawn  from  this  is  clear,  and 
is  indeed  admitted:  If  natural  selection  is  capable  of 
explaining  some  formations  it  will  be  capable  also  of 
explaining  all  the  others;  if  all  formations  can  be  ex- 
plained by  natural  selection  alone,  the  inheritance  of 
acquired  characters  becomes  useless  for  the  purpose  of 
explaining  the  transformation  of  species;  consequently 
if  it  is  useless  it  is  very  probable  that  it  does  not  exist 
at  all. 

The  impartial  reader  will  admit  that  this  manner  of 
reasoning  is  deceptive.  Even  if  it  be  proved  that  natural 
selection  must  necessarily  have  been  capable  of  producing 
certain  formations  with  the  help  of  fortuitous  individual 
variations,  it  does  not  follow  that  it  must  also  have  been 
capable  of  producing  all  other  phylogenetic  formations, 
especially  if  they  are  different  in  nature  from  the  former. 
And  even  if  the  proof  were  forthcoming  that  it  is  capable 
of  explaining  by  itself  all  phylogenetic  formations  what- 
ever, it  is  evident  that  even  this  would  not  constitute 

142Weismann :  Ibid.    P.  61. 


180  Inheritance  of  Acquired  Characters 

any  argument  against  the  inheritance  of  .acquired  char- 
acters. The  continuous  electric  current  for  example  can 
be  produced  by  a  battery  as  well  as  by  a  dynamo;  and 
the  fact  that  one  can  always  explain  it  as  having  been  pro- 
duced by  a  battery  does  not  prevent  it  from  being  actually 
produced  by  a  dynamo  in  many  cases. 

This  being  so,  let  us  now  examine  as  succinctly  and 
objectively  as  we  can  each  of  the  four  arguments : 

1.  No  value  can  be  attributed  to  the  fact  of  the 
exercise  of  a   function  only  a  single  time  during  life. 
In  the  first  place,  it  is  possible  that  it  may  formerly  have 
been  exercised  repeatedly  by  the  ancestors  of  individuals 
now  living.     In  the  second  place  this  singleness   does 
not  exclude  in  any  way  its  inheritance  as  a  habit  acquired 
by  exercise.     For  the  fact  of  having  performed  a  given 
function  even  though  only  a  single  time,  would  certainly 
leave  in  the  parent  organism  a  potential  disposition  to 
perform  it  again  and  with  greater  facility  in  similar 
physiological  and  external  circumstances;  therefore 
the  conception  that  this  disposition  and  this  greater 
facility  would  be  represented  in  descendent  organisms 
represents  only  an  ordinary  case  of  inheritance. 

2.  As    for   the   second   argument   one   cannot   but 
recognize  that  for  certain  formations  the  statement  of 
Weismann  that  they  can  be  due  only  to  natural  selection 
seems  very  probably  true. 

But  it  must  be  remarked  that  to  support  his  assertion 
Weismann  attributes  a  merely  passive  function  to  many 
parts  in  which  it  is  very  questionable. 

Why  for  instance  should  we  not  regard  the  carapace 
of  the  turtle  as  a  true  and  functional  adaptation  due  to 
the  stimulus  of  the  environment  to  which  the  skin  of 
the  animal  had  reacted  by  a  secretion  constantly  richer 


Consideration  of  Weismanris  Arguments        181 

in  hard  substance,  exactly  as  the  skin  of  the  sheep  reacts 
by  the  secretion  of  wool?  There  is  nothing  to  prevent 
such  secretions,  produced  through  functional  adaptations, 
serving  later  as  protective  shields  and  thus  becoming 
useful  to  the  species  in  still  another  way. 

On  the  other  hand  the  envelopes  into  which  the 
crustaceans  and  insects  cited  by  Weismann  insert  one 
part  of  their  body  might  preserve  the  external  surface 
of  that  part  from  the  hardening  action  of  external  agents, 
just  as  houses  and  clothes  may  have  contributed  to  the 
disappearance  of  the  hair  in  man.  For  one  should  not 
consider  the  passive  function  of  the  hair  or  of  the  chiti- 
nous  substance  so  much  as  the  active  function  of  the 
tissues  which  secrete  these  substances;  and  this  function 
is  essentially  active  for  it  is  a  specific  reaction  to  external 
influences. 

In  this  respect  the  hermit  crab  constitutes  one  of  the 
most  conclusive  proofs  of  the  Lamarckian  theory.  For 
this  crab  which  is  accustomed  to  insert  the  hinder  part 
of  his  body  into  empty  snail  shells  has  completely  adapted 
itself  to  the  conformation  of  its  new  habitation,  and  this 
bodily  adaptation  acquired  by  it  has  become  hereditary 
so  that  it  is  present  in  advance  before  the  animal  inserts 
itself  into  its  house.  According  to  Weismann's  view, 
the  animal  must  have  first  adopted  the  habit  and  natural 
selection  must  have  been  able  to  exert  its  influence  only 
subsequently.  Clearly  both  processes  must  go  on  at  the 
same  time,  the  residence  in  the  new  habitation  and  the 
adaptation  to  it;  and  the  fact  that  these  exist  together 
can  be  explained  only  through  functional  adaptation  and 
inheritance  of  its  effects.143 

143G.  Cattaneo:    I  fattori  della  evoluzione  biologica.     P.  43 — 4$; 


1 82  Inheritance  of  Acquired  Characters 

Similarly,  how  can  one  escape  attributing  the  colors 
of  butterflies'  scales  to  functional  adaptation  when  one 
sees  the  golden  red  butterfly  Polyommatus  phlaeas  change 
its  color  and  take  on  a  black  tint  merely  from  transporting 
it  to  warmer  climates? 

Further,  indubitable  instances  are  known  in  which 
the  color  of  the  environment  stimulates  the  outer  surface 
of  the  animal  directly  or  indirectly  to  take  on  the  same 
color.  Thus  some  arctic  animals  and  birds  become  per- 
fectly white  in  winter,  putting  themselves  thus  in  con- 
formity with  the  general  color  of  the  environment. 
Certain  butterflies  present  phenomena  of  protective  poly- 
chromatism  in  the  sense  that  they  always  take  on  the 
color  of  their  environment,  and  this  should  not  appear 
strange  for  there  is  nothing  inadmissible  in  the  sup- 
position that  a  very  sensitive  skin  can  suffer  much  greater 
discomfort  when  the  light  rays  which  strike  it  are  of  a 
color  different  from  its  own  than  when  they  are  of  a 
like  color  with  it.  This  discomfort  would  correspond 
to  the  disagreeable  sense  of  heat  or  cold  which  makes 
itself  felt  over  the  surface  of  the  body  when  its  tem- 
perature differs  from  that  of  its  environment. 

Consequently  if  every  functional  adaptation  of  the 
living  substance  to  external  agents  consists  in  such  a 
modification  of  its  own  vital  processes  that  these  find  in 
the  external  agents  no  longer  obstacles  but  rather  co- 
operative stimuli,  one  can  understand  the  tendency  of 
every  especially  sensitive  organ  to  make  the  color  of 
its  surface  conform  with  that  of  its  environment.  This 
would  not  prevent  the  identity  of  colors  from  being  of 

and  Cesare  Lombroso :  Ancora  dei  caratteri  acquisiti ;  Paguri,  Cam- 
melli  e  Zebu.  Rivista  di  Scienze  Biologiche.  Vol.  II,  No.  3.  1900. 
P.  2-3. 


Consideration  of  Weismann's  Arguments         183 

service  to  the  animals  in  a  protective  way  also,  but  never- 
theless the  productive  cause  would  remain  always  a 
functional  adaptation. 

From  the  preceding  instances  in  which  the  action  of 
the  color  of  the  environment  upon  the  external  surface 
of  the  animal  appears  to  be  direct  we  pass  on  to  those 
in  which  this  action  is  indirect.  Thus  many  fishes, 
amphibians,  reptiles  and  cephalopods  are  capable  of 
changing  their  color  in  a  very  short  time  and  thus  of 
putting  themselves  always  in  accord  with  the  very  vari- 
able color  of  the  environment.  The  color  of  the  environ- 
ment which  determines  that  of  the  animal  does  not  act 
nevertheless,  in  this  case,  directly  upon  the  elements  of 
the  skin,  the  chromoblasts,  which  produce  the  color;  but 
by  a  complicated  nervous  apparatus  connecting  these 
elements  with  the  part  which  is  first  stimulated  by  the 
color.  This  part  is  sometimes  constituted  merely  by 
the  nerve  ends  of  the  skin,  at  other  times  by  the  retinal 
nerve  ends  of  the  eye.  In  the  latter  case  if  the  optic 
lobes  of  the  brain  are  artificially  destroyed  the  capacity 
of  changing  color  disappears.144 

Further,  according  to  LeDantec,  many  colorations  of 
the  skin  that  are  now  fixed  and  correspond  to  the  hence- 
forth unchanging  color  of  the  environment  are  derived 
from  former  colors  that  changed  voluntarily  with  the 
different  colors  of  the  environment,  of  which  one  certain 
color  has  remained,  persisting  to  the  exclusion  of  all  the 
others.145 

One  could  perhaps  also  adopt  the  opposite  view.    Just 

144Weismann :  The  Effect  of  external  Influences  upon  Develop- 
ment. P.  26 — 27. 

145Le  Dantec :  Lamarckiens  et  Darwiniens.  Paris,  Alcan,  1904, 
Chap.  XIV :  Le  mimetisme  lamarckien.  P.  129 — 149. 


184  Inheritance  of  Acquired  Characters 

as  the  secretion  of  gastric  juice  was  originally  a  func- 
tional adaptation  of  the  wall  of  the  stomach  to  certain 
foods  but  finally  is  poured  out  before  the  foods  them- 
selves are  ingested  but  only  tasted,  in  consequence  of 
psychic  associations;  so  the  assimilation  to  the  color  of 
the  environment,  which  originally  was  a  functional 
adaptation  of  the  elements  of  the  skin  producing  the 
color,  the  chromatophores,  may  have  gradually  come  to 
be  produced  in  anticipation  and  finally  exclusively  by 
the  perception  through  the  eyes  of  the  color  of  the 
environment. 

However  that  may  be,  all  these  facts  show  that  far 
from  seeing  in  the  protective  colors  of  animals  merely 
the  result  of  fortuitous  variations  which  have  become 
fixed  by  natural  selection  just  for  their  passive  protective 
function,  we  have  legitimate  reason  for  holding  on  the 
contrary  that  usually  they  are  the  direct  result  of  true 
functional  adaptation. 

In  this  way  would  be  explained  the  possibility  that 
as  soon  as  the  color  of  the  environment  alters,  the  pro- 
tective color  of  the  animal  might  also  become  unstable 
or  disappear  entirely,  and  one  would  not  be  compelled 
to  resort  for  the  explanation  of  the  phenomenon,  as 
Weismann  is,  to  panmyxia  or  to  any  other  complicated 
process  of  natural  selection.  For  this  tendency  to  give 
up  the  color  can  in  this  case  also  be  attributed  to  the 
simple  circumstance  that  when  the  color  of  the  environ- 
ment was  altered  the  functional  stimulus  ceased,  which 
was  the  sole  cause  of  the  color  of  the  animal. 

It  is  true  that  Weismann  points  out  certain  cases 
of  more  typical  mimicry  which  seem  to  prove  the  cor- 
rectness of  his  views  very  especially  because  they  seem 
to  show  that  natural  selection  had  undoubtedly  been 


Consideration  of  Weismann's  Arguments        185 

alone  sufficient  to  produce  in  some  instances  extraor- 
dinarily complicated  formations  down  to  the  most  minute 
peculiarities.  The  example  of  Kallima,  a  well  known 
leaf-like  butterfly,  will  at  once  occur  to  every  one.  Never- 
theless it  is  known  that  certain  Lamarckians  have  had 
the  hardihood  to  wish  to  attribute  these  very  perfect 
resemblances  to  former,  voluntary,  chromoblastic,  mime- 
tic changes  which  do  not  now  exist  in  the  animal  but 
which  can  be  demonstrated  even  now  in  certain  other 
animals,  for  instance  in  some  fishes.  The  absence  of 
change  in  the  object  taken  as  a  model  which  was  imitated 
only  voluntarily  at  first,  has  resulted  in  the  gradual  with- 
drawal of  the  imitative  color  mechanism  from  the  con- 
trol of  the  animal's  will.146  Here  it  is  sufficient  to 
remark  that  the  last  word  has  certainly  not  yet  been  said 
upon  this  voluntary  mimicry  which  rightly  excites  the 
greatest  interest.  In  any  case  such  imitative  formations 
as  that  of  Kallima  cannot  be  disposed  of  by  simply  refer- 
ring them  to  natural  selection  alone,  seeing  that  their 
protective  utility  can  commence  to  be  manifested  only 
after  they  have  attained  an  advanced  degree  of  perfection. 
"A  muscle,"  insists  Weismann,  "can  become  greater 
by  use,  but  a  claw,  a  bristle  border,  a  dentition,  a  pro- 
tuberance at  an  articulation,  cannot  become  thicker, 
longer  or  stronger  by  usage,  it  can  only  be  used  up."  147 
But  does  not  the  very  use  of  these  inactive  parts  tfr, 
better,  the  transmission  through  the  inert  substance  to 
the  living  substance  of  the  mechanical  action  constituted 
by  this  repeated  use,  provoke  the  living  tissue  to  secrete 
in  larger  quantity  the  chitinous  substance  of  the  bristles 
and  of  the  claws? 

14'Le  Dantec:  Lamarckiens  et  Darwinians.     P.  142 — 145. 
147Weismann :  Neue  Gedanken  zur  Vererbungsfrage.    P.  65. 


1 86  Inheritance  of  Acquired  Characters 

"I  need  not  recall,"  continues  our  author,  "the  host 
of  positive  changes  undergone  by  plants  which  cannot 
be  explained  by  the  Lamarckian  theory, — the  appropri- 
ately placed  protective  spines,  bristles  and  hairs,  the 
poisons,  the  tannins,  the  etherial  oils  of  all  kinds,  and 
all  the  purposeful  forms  of  leaves,  of  flowers  and  all 
parts  of  plants  in  general.  In  the  case  of  all  these  the 
supposed  inheritance  of  the  effects  of  use  and  disuse 
in  general  does  not  come  into  question;  in  them  every- 
thing proceeds  without  it, — an  incontestable  proof  that 
nature  does  not  require  this  supposed  factor  for  its  trans- 
formations." 148  It  is  probable  on  the  contrary  that 
many  of  these  changes  undergone  in  the  past  or  in  the 
characters  now  existing  are  rather  simply  the  result  of 
the  reaction  of  the  plant  organs  to  a  certain  external 
or  internal  stimulus  which  has  not  yet  been  remarked 
nor  indeed  suspected.  To  this  category  belong  very 
probably,  for  instance,  all  the  various  secretions  of 
chemical  substances.  Further  the  very  fact  that  secre- 
tions that  are  entirely  alike  occur  in  plant  species  that 
are  quite  unlike  one  another  in  everything  else,  speaks, 
as  we  shall  see  at  once,  in  favor  of  the  hypothesis  that 
these  same  secretions  are  acquired  and  inherited  char- 
acters. Other  characters  which  likewise  were  formerly 
in  all  probability  functional  adaptations  or  are  such  now 
can  incidentally  serve  other  purposes  and  can  therefore 
be  useful  to  the  species  in  other  ways  also,  as  we  stated. 

It  is  evident  that  Weismann,  in  order  to  support  his 
assertion  that  natural  selection  is  quite  capable  of  ex- 
plaining by  itself  the  transformation  of  species,  has 
allowed  himself  to  be  misled  into  denying  arbitrarily 

148Weismann :  Neue  Gedanken  zur  Vererbungsfrage.     P.  66. 


Consideration  of  Weismann' s  Arguments    •  187 

to  a  large  number  of  modifications,  which  do  not  differ 
in  their  essence  from  the  others,  the  character  of  func- 
tional adaptations.  We  would  not  deny  that  there  are 
certain  forms  or  structures,  which,  just  because  their 
functional  character  has  not  been  perceived,  have  not 
heretofore  received  any  explanation  except  through  nat- 
ural selection,  even  though  it  does  not  always  furnish 
an  altogether  satisfactory  explanation.  But  the  deeper 
one  goes  into  the  essence  of  functional  adaptation  and 
the  wider  its  field  of  action  is  seen  to  be,  the  number  of 
these  formations  become  less  and  less  and  with  it 
dwindles  away  also  this  seeming  almightiness  to  explain 
all  physiologic  transformations  whatever,  which  Weis- 
mann  would  like  to  attribute  to  natural  selection  without 
producing  proof  for  it. 

3.  The  third  argument  based  upon  the  neutral  indi- 
viduals of  ants,  bees  and  termites  is  well  known  as  the 
chief  question  about  which  turned  the  polemic  between 
Weismann  and  Spencer.  The  latter  brought  up  as  one 
of  the  strongest  arguments  in  favor  of  inheritance,  the 
co-adaptation,  that  is  the  co-ordinated  modification  of 
different  parts  co-operating  to  produce  a  definite  physio- 
logical result.  Weismann  on  the  contrary  sees  in  the 
existence  of  neutral  individuals  among  the  ants,  termites 
and  bees  a  refutation  of  Spencer's  theory,  since  these 
individuals  in  the  course  of  their  phylogenetic  develop- 
ment have  undergone  harmonious  modifications  of  di- 
verse parts,  without  ever  having  been  capable  of  repro- 
duction. To  this  Spencer  replied  that  all  the  harmonious 
modifications  of  different  parts,  including  the  numerous 
instincts  which  the  neutrals  present  to-day,  are  only  the 
heritage  of  those  which  the  ancestors  of  these  now  social 
insects  acquired  in  a  state  of  isolation  or  in  a  society  in 


1 88  Inheritance  of  Acquired  Characters 

which  there  was  equality  and  in  which  there  were  no 
castes,  the  neutrals  being  nothing  else  than  females 
incompletely  developed  because  of  defective  nutrition. 

It  would  not  be  correct  to  state  that  the  question 
has  been  finally  decided  through  this  debate.  While 
Weismann  has  not  been  able  to  prove  conclusively  that 
these  harmonious  modifications  of  the  neutrals  have  been 
at  least  partially  acquired  after  the  development  of  castes 
and  when  the  sterility  of  the  neutrals  had  already 
appeared,  neither  has  Spencer  been  able  to  demonstrate 
that  all  these  harmonious  modifications  had  been  already 
acquired  by  the  presocial  ancestors.  Nevertheless  the 
conception  of  Spencer  that  the  neutrals  are  produced  by 
an  arrest  of  development  of  the  females  has  in  our 
opinion  won  a  decisive  victory  over  that  of  his  opponent, 
and  has  in  reality  taken  from  the  last  rampart  of  the 
Weismannists  all  the  strength  which  it  had  derived  from 
the  conception  that  the  neutrals  were  special  formations, 
which  had  acquired  special  characters  by  fortuitous  vari- 
ations and  natural  selection  only. 

4.  The  fourth  and  last  argument,  that  of  the  incon- 
ceivability of  the  transmission  of  acquired  characters,  has 
already  been  considered  by  Darwin  in  connection  with 
examples  which  he  had  himself  communicated  of  the 
inheritance  of  certain  peculiarities,  particularly  of  instincts 
acquired  by  domestic  animals.  " Nothing  in  the  whole 
circuit  of  physiology,"  he  stated  in  this  connection,  "is 
more  wonderful.  How  can  the  use  or  disuse  of  a  partic- 
ular limb  or  of  the  brain  affect  a  small  aggregate  of 
reproductive  cells  seated  in  a  distant  part  of  the  body, 
in  such  a  manner  that  the  being  developed  from  these 
cells  inherits  the  characters  of  either  one  or  both  parents  ? 


Consideration  of  Weismann's  Arguments       189 

Even  an  imperfect  answer  to  this  question  would  be 
satisfactory."  149 

This  argument  which  Weismann  considered  as  the 
strongest,  without  indeed  saying  so  definitely  but  allow- 
ing it  to  be  seen,  is  in  reality  the  feeblest  of  all.  Even 
admitting  that  the  mechanism  of  transmission  may  be 
at  present  quite  inconceivable,  that  is  no  reason  for  believ- 
ing that  it  does  not  exist,  since  the  number  of  phenomena 
and  even  of  natural  laws  which  we  must  regard  as  cer- 
tainly established,  even  though  we  cannot  so  far  explain 
them  in  any  way  is,  one  can  well  say,  infinite.  It  recalls 
the  former  objection  to  Newton's  theory  that  it  is  incon- 
ceivable how  the  heavenly  bodies  could  mutually  attract 
one  another  at  such  a  distance,  and  like  this  it  is  of  no 
logical  value.  Apart  from  this  it  can  have  only  one 
very  important  practical  consequence,  (and  it  has  had 
this  effect  and  as  a  matter  of  fact  is  still  producing  it), 
i.  e.  of  bringing  the  reality  of  this  inheritance  into  ques- 
tion with  very  many  investigators  and  stimulating  them 
therefore  to  a  zealous  search  for  a  conclusive  experiment 
which  should  once  for  all  establish  or  exclude  it. 

In  any  case  it  is  interesting  to  note  that  Nussbaum 
whose  theory  of  the  continuity  of  the  germ  cells  sug- 
gested to  Weismann  his  fundamental  conception  of  the 
continuity  of  the  germ  plasm,  is  opposed  to  him  in  that 
he  dees  not  exclude  the  possibility  of  the  transmission 
of  acquired  characters.  For  immediately  after  the  expo- 
sition of  his  theory  he  states  "since  seeds  and  eggs  are 
stored  up  in  the  parent  organism,  they  are  therefore 
subjected  to  the  action  of  conditions  which  bring  about 

149Warwin :  The  Variation  of  Animals  and  Plants  under  Domes- 
tication, H.  P.  367. 


190  Inheritance  of  Acquired  Characters 

modifications  of  it,  and  so  the  transmission  of  acquired 
characters  is  not  excluded."  15° 

After  thus  having  brought  forward  and  refuted  the 
four  principal  arguments  adduced  by  Weismann  against 
the  Lamarckian  theory,  we  must  now  examine  the  value 
of  the  corollaries  and  subsidiary  theories  which  this 
investigator  devised  to  defend  his  doctrine  from  the  mani- 
fold objections  which  were  brought  forward  from  all 
sides  to  show  its  inadmissability. 

Panmixia  presents  itself  as  the  first  subsidiary 
theory.  It  has  entirely  succumbed.  It  was  devised  by 
Weismann  to  explain  the  progressive  phyletic  atrophy  of 
the  organs  which  have  become  useless,  and  rests  on  the 
supposition  that  as  soon  as  the  fortuitous  variation  of  a 
certain  organ  has  become  useless  for  the  species,  and  is 
therefore  withdrawn  from  natural  selection,  the  minus 
variations  which  this  organ  would  chance  to  present  in 
certain  individuals  would  no  longer  cause  the  disappear- 
ance of  these  latter  in  the  struggle  for  existence.  The 
survival  of  organisms  with  such  minus  variations  and 
their  sexual  union  with  individuals  which  still  preserve 
the  organ  in  its  original  state  would  lead  gradually  to 
the  degeneration,  progressive  atrophy  and  final  disappear- 
ance of  the  organ. 

Spencer,  nevertheless,  rightly  draws  attention  to  the 
fact  that  the  appearance  of  plus  variations  is  just  as 
probable  as  that  of  minus  variations,  and  therefore  pan- 
mixia is  not  at  all  capable  of  explaining  by  itself  this 
progressive  and  continuous  degeneration  of  useless 
organs. 

1BONu£baum:  Zur  Differenzierung  des  Geschlechts  im  Tierreich. 
Arch.  f.  mikr.  Anat,  Bd.  18.  Erstes  Heft.  Bonn.  Cohen.  1880. 
P.  113- 


Panmixia  and  the  Principle  of  Economy        191 

The  addition  suggested  by  Romanes  that  the  tendency 
to  atavistic  reversion  favors  minus  variations  at  the 
expense  of  plus  variations,  does  not  suffice.151  For  in 
the  first  place  an  atavistic  reversion  could  appear  at  best 
only  in  the  phyletic  characters  acquired  last,  and  in  the 
second  place,  after  the  first  stages  of  atrophy  had  ap- 
peared it  would  in  any  case  tend  from  that  time  on  to 
insure  the  preponderance  of  plus  over  minus  variations. 

One  could  nevertheless  assert  that  panmixia  is  not 
necessary  for  Weismann's  theory.  The  principle  of  the 
economy  of  the  organism  by  which  every  useless  and 
unused  organ  is  harmful  because  it  withdraws  nourish- 
ment from  other  organs  is  by  itself  enough,  if  one 
rejects  the  inheritance  of  acquired  characters,  to  explain 
the  gradual  phyletic  disappearance  of  useless  parts. 

But  this  hypothesis  is  easily  refuted  by  some  calcula- 
tions of  Spencer,  showing  that  it  is  impossible  that  the 
advantage  to  the  organism  of  a  small  inborn  and  fortu- 
itous minus  variation  in  the  useless  organ,  particularly 
when  this  is  already  very  much  degenerated  as  is  for 
instance  the  hind  leg  of  the  whale,  can  procure  for  the 
individual  an  advantage  over  others  and  so  provoke  the 
phylogenetic  passage  to  a  yet  greater  atrophy.  And  no 
great  value  can  be  attributed  to  the  counter  observation, 
which  Weismann  several  times  repeats,  that  we  are  still 
quite  unable  to  measure  the  selective  efficacy  of  the 
struggle  for  existence.  One  need  think  only  of  the 
parasites  and  particularly  of  the  endoparasites,  which 
have  always  an  excess  of  nutrition  and  in  which  there- 
fore the  advantage  of  the  degeneration  of  useless  organs 
would  become  reduced  absolutely  to  zero.  And  it  is 

1B1Romanes :  A  Note  on  Panmixia.  Contemporary  Review.  Octo- 
ber 1893.  P.  612. 


192  Inheritance  of  Acquired  Characters 

nevertheless  in  these  that  this  reduction  reaches  its 
maximum. 

However  that  may  be,  we  might  nevertheless  admit 
either  that,  as  panmixia  supposes,  fortuitous  minus 
variations  preponderate  over  plus  variations,  or  that  the 
principle  of  the  economy  of  the  organism  is  alone  enough 
to  secure  the  victory  to  those  individuals  whose  useless 
organs  are  most  atrophied.  But,  even  in  that  case  how 
could  panmixia  and  the  principle  of  economy  in  the 
organism  explain  the  fact  that  the  atrophic  state  of 
organs  which  have  become  useless,  such  as  appears  in 
adult  organisms,  results  in  the  course  of  ontogeny  from 
an  involutive  process  of  these  organs  which  are  better 
developed  in  the  early  stages  than  in  the  later  stages? 
Although  in  so  doing  we  anticipate  a  question  which  we 
shall  examine  again  later  in  all  its  generality,  we  may 
note  here  that  the  most  that  panmixia  and  the  principle 
of  economy  could  do  would  be  to  explain  the  fact  that 
the  more  recent  a  species  with  a  given  atrophied  organ 
is,  the  earlier  should  be  the  stage  of  development  at 
which  the  organ  in  question  is  arrested  in  ontogeny, 
whereas  in  the  ancestral  species  it  attained  a  greater 
development.  But  how  can  they  explain  how  certain 
tissues  and  organs  develop  during  ontogeny  up  to  a 
certain  and  fairly  advanced  point  and  thereafter  at  a 
certain  moment  undergo  a  physiologic  involution  result- 
ing in  their  degeneration  and  often  in  their  complete 
disappearance  ? 

As  we  pass  on  now  from  continuous,  gradual  atrophy 
of  useless  organs  to  the  slowly  progressive  formation  of 
useful  organs  and  so  to  phyletic  evolution  in  general,  we 
must  declare  at  the  outset  that  of  all  the  objections  that 
have  been  urged  and  which  can  yet  be  urged  against  the 


All  Sufficiency  of  Natural  Selection  193 

view  that  natural  selection  by  itself  is  sufficient  to  account 
for  the  transformation  of  species,  we  shall  bring  forward 
only  a  very  small  number.  For  we  believe  it  worth 
while  to  limit  ourselves  to  the  most  characteristic  and 
certain  ones,  which  serve  better  than  the  others  as  an 
indirect  support  for  the  Lamarckian  theory.  And  so 
much  the  more  since  in  the  case  of  many  objections  dis- 
cussion is  idle.  For — and  this  may  be  said  once  for  all 
— if  our  adversary  adopts  the  complete  sufficiency  of 
natural  selection  both  as  his  thesis  and  as  the  ground 
for  the  defense  of  this  thesis,  naturally  it  will  be  very 
difficult,  indeed,  often  quite  impossible  for  us  to  carry 
on  the  contest  from  a  purely  logical  standpoint. 

Candidly  one  could  wish  that  Weismann  would  prove 
this  omnipotence  of  natural  selection  by  some  facts.  But 
he  has  still  to  furnish  this  proof.  For,  as  we  have  seen, 
he  has  limited  himself  to  showing  that  among  the  various 
hypotheses  which  have  been  devised  to  give  account  for 
certain  special  formations,  natural  selection  is  the  one 
which  fulfills  this  purpose  relatively  best. 

But  when  once  our  adversary  sets  up  this  almighti- 
ness  of  natural  selection  as  an  axiom,  to  be  employed 
at  need  as  thesis  or  as  the  support  of  the  thesis,  it  will 
then  be  very  difficult,  we  repeat,  in  most  cases  to  point 
out  any  contradiction  in  his  tenets,  which  is  the  only 
means  by  which  a  logical  refutation  can  proceed  and 
reach  any  result.  In  other  words,  if  in  order  to  demon- 
strate the  complete  sufficiency  of  selection  Weismann 
starts  off  with  the  supposition  that  natural  selection  is 
omnipotent,  how  can  one  by  pure  reasoning  convict  him 
of  error? 

And  in  fact:  One  investigator  offers  the  objection 
that  fortuitous  variations  even  though  they  are  useful 


194  Inheritance  of  Acquired  Characters 

must  nevertheless  in  many  cases  be  so  inconsiderable 
in  amount,  that  they  could  not  possibly  constitute  such 
an  advantage  as  to  give  natural  selection  anything  to  act 
on.  But  Weismann  in  order  to  extricate  himself  from 
this  embarassment  needs  only  to  repeat  here  again  his 
habitual,  axiomatic,  already  mentioned  reply  that  we 
are  unable  to  measure  the  degree  of  selective  power  of 
the  struggle  for  existence. 

Others  object  that  certain  characters  due  to  functional 
adaptation  are  altogether  useless  to  the  species.  One 
can  conceive  how  they  might  be  inborn  in  individuals 
if  one  admits  the  inheritance  of  acquired  characters, 
whereas  they  would  be  quite  inexplicable  if  one  sought 
to  ascribe  them  to  natural  selection  alone.  But  Weis- 
mann has  always  the  answer  at  hand  that  one  cannot 
judge  of  their  present  or  past  usefulness.  A  typical 
example  of  these  discussions  which  logical  processes  are 
powerless  to  decide  is  the  question  debated  in  the  Spencer- 
Weismann  polemic  upon  the  especially  acute  taste  sense 
of  the  tongue  papillae.  While  Spencer  attributes  it  to 
the  continual  rubbing  of  the  tongue  against  the  teeth 
and  states  that  it  is  without  utility  for  the  organism; 
Weismann  on  the  contrary  asserts  that  it  may  have  been 
of  some  use,  at  least  in  the  past.  We  do  not  forget  in 
this  connection  that  the  question  might  also  be  raised 
whether  this  fine  sense  of  taste  is  really  inborn  or  is 
not  rather  acquired  anew  in  each  individual  after  birth. 

Others  regard  natural  selection  as  powerless  to  bring 
about  any  transformation  because  the  fortuitous  vari- 
ations or  individual  deviations,  upon  which  it  is  able  to 
act,  are  constantly  destroyed  by  amphimixis.  Weismann 
can  always  reply  that  the  fortuitous  variations  or  devi- 
ations preserved  in  an  individual  by  natural  selection  are 


Amphimixis  and  Nutritive  Irregularities  in  Germs  195 

not  prevented  from  passing  to  descendants  by  the  con- 
jugation of  this  individual  with  others  which  do  not 
possess  any  such  variations,  but  are  only  diluted,  so  to 
speak.  Therefore  all  that  is  necessary  is  to  suppose  the 
struggle  for  existence  to  be  more  severe  or  to  have  a 
higher  degree  of  selective  capacity  than  that  which  would 
have  been  sufficient  if  there  had  not  been  sexual  repro- 
duction. 

It  is  well  known  further  that  Weismann,  in  order 
to  afford  natural  selection  abundant  and  never  failing 
material  upon  which  to  act,  has  made  for  himself  a 
weapon  of  sexual  reproduction,  attributing  to  it  a  great 
fruitfulness  in  the  constant  production  of  new  variations. 
But  he  seems  to  have  been  partly  converted  finally  to  the 
opposite  view  of  the  Lamarckians  already  mentioned, 
that  sexual  reproduction  only  contributes  to  securing  the 
unity  and  constancy  of  the  species.  For,  in  order  to  ex- 
plain the  production  of  a  lot  of  fortuitous  variations, 
he  finally  sought  refuge  in  the  unavoidable  irregularities 
of  nutrition  in  the  germ  plasm,152  a  thing  which  makes 
his  hypothesis  upon  the  biologic  function  of  amphimixis 
quite  superfluous.  It  may  be  merely  noted  here  that  when 
once  one  sees  in  amphimixis  a  cause  tending  toward  the 
levelling  of  individual  characters  and  consequently  to- 
ward the  fixity  of  the  species,  and  thereby  reducing  by 
so  much  the  probability  that  the  selective  capacity  of  the 
struggle  for  existence  is  alone  sufficient,  one  must  then 
feel  so  much  the  more  strongly  the  necessity  of  discover- 
ing some  cause  of  variation  capable  of  acting  simul- 
taneously and  in  the  same  way  upon  at  least  quite  a 
large  part  of  the  individuals  of  the  species,  and  of 

162Weismann:  Das  Keimplasma.    P.  541 — 570. 


196  Inheritance  of  Acquired  Characters 

acting  also  in  this  same  direction  throughout  a  decidedly 
large  number  of  successive  generations. 

"One  must  admit,"  says  Hartmann,  very  rightly, 
"that  minute  and  purely  accidental  variations  even  if 
they  are  useful,  are  unable  to  preserve  themselves  from 
disappearing  again  through  crossing.  Whatever  is  to 
be  preserved  must,  as  Darwin  also  admits,  appear  in  a 
certain  quantity,  either  all  at  once  or  successively,  because 
the  number  of  similar  variations  must  be  sufficient  to 
overcome  the  suppression  through  crossing.  But  it  is 
not  to  be  expected  that  similar  variations  will  appear  in 
such  frequence  by  chance,  but  only  as  a  result  of  definite 
external  or  internal  causes  which  set  a  definitely  directed 
modification  in  the  place  of  accidental  ones."  153 

Of  the  causes  of  variation  which  possess  this  capac- 
ity of  simultaneous  similar  and  constant  action,  we  know 
at  present  only  functional  adaptation  aided  by  the  inher- 
itance of  acquired  characters. 

The  very  fixity  of  many  species  has  been  rightly 
urged  against  Weismann.  Natural  selection  in  fact, 
because  of  the  smallness  of  fortuitous  individual  vari- 
ations, is  forced,  on  the  one  side  in  order  to  explain  by 
itself  the  development  of  species,  to  fall  back  upon  an 
excessively  great  degree  of  selective  capacity;  but  on 
the  other  side  if  this  great  degree  of  selective  capacity 
is  accorded,  it  encounters  still  greater  difficulty  in  account- 
ing for  the  contrary  phenomenon  presented  by  a  host  of 
other  species  which  have  remained  unaltered  even  dur- 
ing a  whole  series  of  long  geologic  periods. 

The  Lamarckian  theory  does  not   find   any   special 

1BSEduard  von  Hartmann:  Die  Abstammungslehre  seit  Darwin. 
Annalen  der  Naturphilosophie,  herausg.  v.  W.  Ostwald.  Zvv.  Bd., 
Heft.  III.  Leipzig,  May  26,  1903.  P.  289. 


Transformations  Due  to  Environmental  Changes  197 

difficulty  in  this.  If  the  true  provocation  to  alteration 
comes  from  the  environment  and  not  from  natural 
selection,  the  evolution  of  certain  species  and  the  con- 
stancy of  certain  others  may  be  explained  simply  by  the 
respective  alteration  or  stability  of  their  environment. 

The  alteration  of  the  environment  could  be  brought 
about  in  the  case  of  a  given  species  not  only  through 
natural  telluric  changes  but  also  for  instance  by  the 
migration  of  this  species  toward  other  regions,  or  by  the 
immigration  of  other  species  into  its  territory,  often 
also  by  the  overcrowding  of  its  territory  by  the  species 
itself. 

Emigration  as  a  cause  of  variation  of  environment 
does  not  need  to  be  illustrated  by  examples. 

The  immigration  of  other  species  can  immediately 
induce  a  very  considerable  modification  of  the  environ- 
ment. The  immigration  of  a  bird  of  prey  with  rapid 
flight  will  have  as  a  result  that  the  birds  for  instance  of  a 
certain  native  species  are  compelled  to  fly  more  rapidly 
in  order  to  escape  it.  This  repeated  greater  effort  will 
develop  an  increase  of  their  swiftness,  an  increase  which 
would  not  have  been  attained,  we  must  believe,  by  normal 
daily  exercise.  For  the  normal  exercise  of  a  given 
function  after  the  respective  organ  has  once  been  formed, 
does  not  develop  it  any  further  but  merely  causes  it  to 
preserve  the  degree  of  development  already  attained.  In 
this  way  one  can  readily  see  also  that  if  the  region 
ravaged  by  the  bird  of  prey  is  only  one  part  of  the 
whole  territory  inhabited  by  this  aboriginal  species,  one 
portion  only  of  that  species  will  be  forced  to  become 
transformed  into  a  swifter  variety  while  the  remaining 
portion  can  and  must  remain  unaltered. 

The  overcrowding  of  a  given  territory  by  a  given 


198  Inheritance  of  Acquired  Characters 

species  can  not  only  force  this  species  to  emigrate,  or  at 
least  to  widen  its  range  of  habitation,  thus  placing 
itself  in  contact  with  different  telluric  conditions  and 
with  different  fauna  and  flora,  but  also  it  can  itself 
induce  directly  very  considerable  modifications  of  the 
environment. 

Thus,  to  take  an  already  famous  example,  it  is  pos- 
sible that  the  long  neck  and  forelegs  of  the  giraffe  are 
to  be  ascribed  to  the  overcrowding  of  the  territory 
inhabited  by  its  ancestors.  For  if  we  suppose  that  these 
ancestors  at  a  definite  time  and  in  a  definite  region  had 
become  altogether  too  numerous  in  proportion  to  the 
trees  present  whose  leaves  served  them  for  nourishment, 
then  all  the  leaves  up  to  a  certain  height  would  naturally 
have  been  eaten  first,  and  there  would  finally  remain  only 
those  leaves  situated  very  high,  so  that  in  order  to  reach 
them  the  animal  was  forced  to  stretch  out  its  neck  with 
a  greater  effort  than  formerly  and  to  stand  upon  its 
hind  legs,  falling  later  on  the  fore  legs  after  plucking 
off  the  leaf.  And  these  efforts  so  very  different  from  the 
ordinary  would  have  produced  quite  new  morphological 
adaptations.  But  it  is  not  at  all  necessary  to  suppose 
that  all  the  individuals  of  this  former  species  of  giraffe 
were  forced  indiscriminately  to  this  transformation.  For 
many,  perhaps  becoming  accustomed  to  another  diet,  could 
remain  unaltered  or  undergo  transformations  of  little 
importance. 

In  other  cases,  on  the  contrary,  that  part  of  the 
species  which  was  driven  through  overcrowding  of  the 
territory  to  change  its  diet  would  be  compelled  to  undergo 
the  most  considerable  transformations.  This  would  be 
the  case,  for  example,  when  the  overcrowding  of  a  given 
tract  of  meadow  land  by  a  species  feeding  exclusively 


Consideration  of  Weismanris  Arguments        199 

on  grass  and  herbs  would  force  some  of  these  animals 
to  feed  on  tree  leaves,  others  to  become  transformed  into 
rodents  and  insectivors  or  to  undergo  some  transforma- 
tion of  still  another  kind. 

In  this  connection  it  is  to  be  especially  noted  that 
just  because  a  large  number  of  the  individuals  of  the 
old  species  will  thus  have  come  to  seek  their  nourish- 
ment elsewhere,  no  change  will  appear  in  those  remaining 
behind  in  the  former  conditions  of  nourishment.  In 
other  words  the  elimination  caused  by  the  change  in 
their  habits  of  the  overcrowding  individuals  from  among 
the  company  of  the  old  species  will  leave  the  other 
individuals  of  this  species,  whose  number  will  now  be 
no  longer  too  great,  in  the  same  conditions  of  environ- 
ment as  formerly,  without  any  overcrowding  and  con- 
sequently there  will  not  be  any  further  causes  provoking 
in  these  individuals  also  a  transformation  into  another 
species. 

The  change  of  nutrition  will  induce  then  a  whole 
series  of  changes  in  the  functions  of  seeking  food,  hunt- 
ing, fighting,  seizing,  chewing  etc.,  but  only  for  that 
position  of  the  species  which  has  changed  its  mode  of 
living.  Thus  it  is  clear  how,  during  a  series  of  entire 
geological  periods,  a  certain  number  of  the  ancestors 
of  individual  species  that  are  now  quite  different  from 
them  were  able  to  preserve  themselves  unaltered  and 
so  to  reproduce  their  descendants  unaltered  to  this  day. 

Man  is  distinguished  from  other  animals  perhaps  in 
this,  that  whereas  the  latter  do  not  modify  their  environ- 
ment or  modify  it  only  indirectly  and  intermittently  by 
emigration  or  by  overcrowding  and  consequently  make 
no  progress  in  their  development  so  long  as  their  environ- 
ment undergoes  no  alteration  from  one  of  the  causes 


2OO  Inheritance  of  Acquired  Characters 

mentioned  or  from  some  other  accidental  cause,  man 
on  the  contrary  modifies  his  environment  directly  and 
continuously  by  the  products  of  civilization.  And  this 
unceasing  modification  of  the  environment  results  in  the 
unceasing  evolution  of  the  man. 

It  is  thus  for  example  with  cerebral  development. 
Civilization  itself  and  the  continual  progress  of  science 
and  arts  make  steadily  increasing  demands  upon  the 
brain.  And  this  mental  exercise,  steadily  increasing  from 
generation  to  generation,  contributes  always  to  the 
development  of  the  brain.  What  wonder  then,  if  the 
cranial  capacity  of  man  has  become  markedly  increased 
even  during  the  three  last  centuries,  as  is  stated  by  the 
anthropologists  ? 

Another  cause  whereby  one  portion  of  a  given  species 
can  remain  unaltered  while  the  remaining  portion 
becomes  transformed,  is  found,  when  once  the  inher it- 
ability  of  acquired  characters  is  admitted,  in  the  sudden 
apparition  of  certain  instincts.  "Also  in  the  domain  of 
biology,"  writes  Emery,  "and  very  especially  in  that 
domain,  many  characters  of  organisms  seem  to  me  to 
permit  of  explanation  only  by  sudden  formation.  This 
is  especially  true  of  habits  and  instincts.  How  could 
the  first  Velleius  dilatatus  arrive  gradually  at  its  para- 
sitic life  in  the  nest  of  the  hornet?  The  first  cuckoo 
certainly  commenced  suddenly  to  deposit  its  eggs  in  the 
nest  of  a  strange  bird."  154 

The  first  sudden  appearing  of  a  new  instinct  can  be 
compared  to  a  happy  thought.  It  is  a  definite  association 
of  ideas  which  is  formed  for  the  first  time.  But  when 
it  has  once  been  formed,  it  is  easily  possible  and  indeed 

154Emery:  Gedanken  zur  Deszendenz-  und  Vererbungstheorie. 
Biol,  Centralbl.,  July  15,  1893.  P.  416. 


Appearance  and  Inheritance  of  Instincts          201 

probable  that  it  will  be  formed  often  again  in  the  same 
individual,  and  this  repetition  will  produce  a  constantly 
increasing,  corresponding  modification  of  the  nervous 
tissue  in  the  individual  concerned,  which  will  be  repro- 
duced in  his  descendants.  A  new  association  of  ideas 
can  arise  and  actually  does  arise  independently,  within 
certain  limits,  of  the  nervous  structure  of  the  individual, 
and  therefore  independently  of  the  germ  substance  also 
which  has  produced  this  latter,  in  so  far  as  the  fortu- 
itous external  circumstances  which  produce  this  new 
association  exert  a  strong  and  overmastering  influence: 
Among  a  thousand  individuals,  quite  identical  in  regard 
to  the  structure  of  their  nervous  mechanism,  this  new 
association  of  ideas  will  be  developed  in  only  one,  on 
account  of  the  special  external  circumstances  in  which 
it  happens  to  be  placed. 

But  without  the  inheritance  of  acquired  characters 
this  fortunate  new  association  of  ideas,  and  the  repeated 
employment  of  it  by  the  individual  later,  would  be  com- 
pletely lost  for  the  species.  To  assure  its  transmission 
from  one  generation  to  another  there  would  remain  only 
imitation  or  education  in  the  widest  sense  of  the  word. 
But  the  fact  is  that  nearly  all  the  instincts  are,  on  the 
contrary,  truly  inborn,  that  is  to  say  they  are  produced 
without  any  psychic  educative  influence  whatever. 

It  is  clear  also  that  not  all  the  members  of  the  older 
species  will  be  able  to  make  use  of  a  new,  fortuitously 
developed  instinct  through  educative  imitation  and  later 
through  heredity,  but  only  the  immediate  descendants  or 
associates  of  the  individual  in  whom  it  was  developed. 
All  other  members  of  the  species  would  be  excluded. 
And  so  those  will  be  the  only  ones,  who,  in  consequence 
of  this  newly  adopted  habit,  will  make  a  thorough 


2O2  Inheritance  of  Acquired  Characters 

change  in  their  former  manner  of  life,  and  in  whom 
consequently  the  whole  organism  will  be  modified  through 
functional  adaptation.  In  this  way  may  be  explained 
the  transformation  of  only  one  group  of  the  individuals 
constituting  a  species  into  a  new  species,  while  the  others 
remain  unchanged. 

These  few  examples,  even  though  so  briefly  outlined, 
are  nevertheless  quite  enough  to  show  us  that  the 
Lamarckian  theory  is  capable  of  explaining  at  the  same 
time  both  the  evolution  and  the  fixity  of  a  species.  But 
how  can  Weismann  account  for  the  inalterability  and 
constancy  of  a  given  species?  It  goes  without  saying 
that  he  has  no  hesitation  in  attributing  it,  like  variation 
itself,  to  natural  selection  again.  But  even  if  one  were 
willing  to  suppose  the  environment  immutable,  is  it 
possible  that  any  species  could  ever  come  to  such  a 
degree  of  perfection  in  relation  to  its  environment  that 
every  new  variation  in  any  direction  whatever  must  make 
the  conditions  of  this  species  worse  and  make  its  mem- 
bers less  likely  to  be  victorious  in  the  struggle  for 
existence?  Is  it  not  much  more  probable  that  however 
high  a  degree  of  adaptation  to  its  environment  a  species 
may  have  attained,  it  can  always  become  even  better 
equipped  for  the  struggle  for  existence  through  further 
transformations  in  certain  directions,  and  consequently 
offer  still  greater  opportunities  for  natural  selection 
which  is  everywhere  and  always  upon  the  qui  vive? 

We  must  nevertheless  be  careful,  in  relation  to  this 
question  of  the  fixity  of  species,  not  to  attribute  to  the 
arguments  which  we  have  just  set  forth  any  greater  value 
than  they  actually  possess,  especially  because  we  know 
nothing,  or  only  a  very  little,  concerning  the  immediate 
circumstances  that  have  actually  existed  in  the  develop- 


Adaptations  in  Tissue  Structure  203 

ment  of  even  a  single  species,  and  still  less,  if  that  is 
possible,  concerning  the  true  mode  of  procedure  of  this 
natural  selection  which  is  so  difficult  to  control.  So  that 
we  must  content  ourselves  with  putting  forward  the  views 
which  we  have  just  outlined  merely  as  further  con- 
jectures speaking  in  favor  of  the  Lamarckian  theory, 
without  seeking  to  attribute  to  them  the  value  of  logical 
proof. 

Structural  relations  in  general  and  the  most  remark- 
able ones  in  particular,  such  as  the  static  structure  of 
bone,  of  certain  tendons,  of  certain  membranes,  the 
dynamic  structure  of  the  smooth  and  striated  muscle 
tissues  and  other  similar  formations,  which  represent  the 
most  perfect  functional  adaptation  and  the  best  utilization 
of  the  material  down  to  the  minutest  and  most  delicate 
details,  testify  likewise  in  favor  of  the  transmissibility 
of  acquired  characters.  "All  these  formations  of  con- 
nective tissue,  muscle  and  bone,"  writes  Roux,  "could 
never  have  been  developed  in  such  regularity  and  com- 
pleteness by  Darwinian  selection  from  individual  varia- 
tions of  form,  since  here  there  must  necessarily  have 
been  thousands  of  fibers  and  cellules  already  accidentally 
arranged  in  this  purposeful  fashion  in  order  to  produce 
even  the  smallest  advantage  appreciable  in  the  economy 
and  capable  of  being  acted  upon  by  natural  selection,  and 
so  much  the  more  since  in  the  extremity  of  hunger  these 
would  be  exactly  the  parts,  the  heart  excepted,  which, 
thanks  to  the  small  amount  of  metabolism  in  them, 
would  suffer  last  of  all, — much  later  than  other  more 
vitally  important  organs  with  more  active  metabolism. 
These  formations  could  not  therefore  arise  from  the 
selection  of  individual  variations  in  form,  but  are  rather 
derived  only  from  those  qualities  of  the  respective  tissues 


2O4  Inheritance  of  Acquired  Characters 

to  which  is  directly  due  the  fashioning  of  the  adaptation 
even  to  the  smallest  details."  155 

But  Weismann  could  very  lightly  deny  to  these  very 
perfect  structural  formations  any  value  as  even  indirect 
proof  of  the  principle  of  inheritance.  From  his  point 
of  view  he  needs  only  to  object  that  since  they  are  useful 
to  the  species  they  can  then  be  very  easily  explained  by 
natural  selection  alone,  and  no  refutation  would  be 
possible. 

Inborn  characters  have  the  tendency  to  become  like 
those  which  the  ancestors  acquired  by  functional  adapta- 
tion, and  this  coincidence  speaks  also  in  favor  of  the 
hypothesis  of  the  inheritance  of  acquired  characters.  But 
against  this  also  Weismann  would  have  no  lack  of  words 
and  apparent  arguments. 

Functional  adaptation,  he  could  reply,  renders  the 
species  more  capable  of  resistance.  The  greater  the 
individual  disposition  to  this  adaptation  the  more 
rapidly  the  adaptation  will  proceed.  Consequently  those 
individuals  upon  which  this  disposition  is  especially 
impressed  will  survive,  and  above  all  those  individuals 
in  which  this  adaptation  is  already  existent  potentially 
in  their  germ  plasm.  Thus  the  coincidence  in  question 
could  be  explained  without  requiring  the  adoption  of 
the  inheritance  of  acquired  characters. 

In  this  way  one  would  arrive  at  the  conclusion  that 
all  characters  susceptible  of  being  produced  by  the  innu- 
merable functional  adaptations  must  for  that  very  reason 
be  always  useful  to  the  species,  so  that  they  can  be  fixed 
even  when  they  happen  to  be  actually  produced  by  fortu- 
itous inborn  variation.  We  shall  not  consider  this  further 

1B5Roux :  Der  Kampf  der  Teile  im  Organismus.    P.  30. 


Similarity  of  Adaptations  in  Different  Species    205 

for  it  would  lead  us  back  to  the  question  which  Spencer 
has  raised  with  his  example  of  the  more  acute  sense  of 
taste  in  the  papillae  of  the  tongue,  and  of  which  we  have 
spoken  above.  But  apart  from  that,  is  it  possible  for 
this  argument,  however  unassailable  it  may  be  from  a 
purely  logical  point  of  view,  really  to  weaken  the  strong 
presumption  in  favor  of  transmissibility  which  is  derived 
from  the  fact  tha-t  inborn  structural  relations  always 
follow — though  slowly  and  tardily — those  acquired  in 
life  through  functional  adaptation,  as  the  shadow  follows 
the  body  ? 

Another  fact  among  those  which  speak  most  con- 
vincingly in  favor  of  the  inheritance  of  acquired  char- 
acters is  the  similarity  of  certain  structures  in  different 
species  which  are  subjected  to  the  action  of  the  same 
mechanical  conditions.  Without  needing  to  bring  up 
the  most  typical  and  most  familiar  case,  viz.,  the  trans- 
formation of  the  extremities  of  the  whale  into  fins,  it 
would  be  enough  to  recall  as  examples  the  like  char- 
acter of  the  leg  joints  in  the  two-hoofed  animals 
(Diplartha,  Cope)  and  the  rodents,  which  is  attributed 
to  their  rapid  locomotion;  the  like  structure  of  the 
extremity  of  the  radius  in  the  edentates  and  the  quadru- 
mana  which  possess  the  power  of  supinating  the  hand; 
the  like  reduction  in  number  of  the  digits  in  many 
orders  of  digitigrade  mammals  which  run  about  on  the 
dry  hard  ground ;  the  like  modifications  in  the  form  and 
development  of  crests  on  the  skull  following  like  employ- 
ment of  the  canine  teeth  as  fighting  teeth  in  all  orders 
in  which  these  teeth  are  strongly  developed.156 

156Cope :  The  mechanical  Causes  of  the  Development  of  the  hard 
Parts  of  the  Mammalia.  Journal  of  Morphology,  vol.  VIII,  No.  2. 
Boston,  U.  S.  A.,  Ginn,  Sept.  1899.  P.  159—163,  164—165,  175—176, 
182—183,  201—203,  273. 


206  Inheritance  of  Acquired  Characters 

For  if  these  structures  had  all  arisen  through  nat- 
ural selection  only,  selecting  the  most  fit  from  among  all 
the  chance  variations,  one  could  not  explain  how,  in 
different  species,  even  though  they  were  subjected  in 
respect  to  that  particular  organ  to  like  mechanical  con- 
ditions, it  could  lead  to  one  and  the  same  result.  In 
fact  how  could  one  affirm  that  the  structure  of  any  given 
organ  must  be  of  one  certain  character  only  and  no  other, 
in  order  to  render  the  species  most  fit  for  the  struggle 
for  existence?  So  mere  chance  must  be  invoked  to 
account  for  the  fact  that  of  the  numerous  structures 
among  which  natural  selection  could  choose,  it  has 
selected  in  the  most  different  species  subjected  to  the 
action  of  the  same  mechanical  conditions  in  relation  to 
only  one  of  their  organs,  just  one  single  structure  for 
this  organ,  absolutely  alike  for  all  these  different  species. 

A  similar  phenomenon,  which  leads  one  toward  the 
same  view,  is  mentioned  by  DeVries,  as  already  noted, 
in  support  of  his  theory  of  pangens  or  preformistic 
germs,  representative  of  definite  characters ;  namely,  that 
the  most  diverse  species  of  plants  have  often  the  power 
of  producing  a  greater  or  less  number  of  identical  chem- 
ical compounds.  "Insectivorous  plants,  for  example, 
belong  to  the  most  different  natural  families,  neverthe- 
less they  all  possess  the  faculty  of  producing  from  their 
leaves  the  necessary  mixture  of  an  enzyme  and  an  acid 
requisite  for  dissolving  albuminous  bodies."  157  Darwin 
himself  has  already  remarked  that  this  mixture  is  quite 
similar  to  the  gastric  juice  of  the  higher  animals. 

Now  without  wishing  to  touch  anew  upon  the  ques- 
tion of  preformistic  germs  which  we  have  already  dis- 

167De  Vries :  Intracellulare  Pangenesis.     P.  8— 10. 


Similarity  of  Adaptations  in  Different  Species      207 

cussed,  it  may  merely  be  remarked  here  that  the  existence 
of  these  like  properties,  acquired  in  the  most  different 
species,  is  easier  to  explain  by  the  Lamarckian  theory  than 
by  natural  selection.  For  just  as  substances  exposed,  for 
example,  to  identical  calorific  influences  finally  all  take 
on  the  same  degree  of  temperature,  and  yet  all  remain 
quite  different  from  one  another  in  other  characters, 
so  when  quite  different  species  are  exposed,  on  account 
of  the  environment,  or  nourishment,  or  peculiar  condi- 
tions of  light,  or  of  any  other  cause  whatever,  to  func- 
tional stimuli  which  incite  them,  for  example,  to  secrete 
tannic  acids  or  alkaloids,  and  so  on,  these  secretions, 
acquired  by  means  of  functional  adaptation  and  trans- 
mitted later  by  heredity,  must  come  to  be  present  in 
several  species,  'even  though  all  other  characters  can 
remain  different. 

Here  it  seems  to  us,  there  remains  for  Weismann 
nothing  else  than  to  affirm  that  these  like  characters 
may  have  been  fixed  by  natural  selection  in  the  most 
different  species  because,  from  the  likeness  of  the  func- 
tional stimuli  to  which,  according  to  the  hypothesis,  these 
species  were  exposed,  the  same  characters  must  have 
been  the  most  useful  for  every  one  without  exception. 
But  this  must  first  be  proved.  And  so  much  the  more 
since  in  this  case  it  is  more  difficult  than  in  other  cases 
to  see  the  absolute  necessity  that  all  characters  or  pecu- 
liarities whatever,  which  are  due  to  the  reaction  of  the 
organism  to  the  most  different  external  influences  and 
often  to  insignificant  ones,  must  always  be  useful  to 
the  individual,  and  that  therefore  they  must  also  possess 
this  utility  even  when  they  are  produced  rather  by  means 
of  inborn  fortuitous  variations. 

If  the  soundness  of  this  conception,  required  by  the 


208  Inheritance  of  Acquired  Characters 

theory  of  Weismann,  of  the  selective  utility  of  every 
inborn  character  which  happens  to  be  a  repetition  of  a 
functional  adaptation  induced  by  reaction  to  any  external 
influence  whatever,  is  very  doubtful,  and  in  any  case  far 
from  having  yet  been  proved;  yet  the  utility  of  one  part 
of  these  acquired  characters  is  proven  and  indubitably 
established.  And  indeed  it  is  just  from  this  utility  that 
one  of  the  strongest  arguments  against  the  presumed 
non-inheritance  of  acquired  characters  is  derived. 

Since  in  fact  the  usefulness  of  some  functional 
adaptations  to  the  individual  is  great  and  sometimes 
extremely  great,  it  must  immediately  follow  from  that, 
according  to  Weismann's  view,  that  the  inheritance  of 
acquired  characters  is  itself  the  result  of  natural  selection. 
For  the  species  in  which  this  inheritance  began  to  mani- 
fest itself  even  though  to  a  slight  extent  would  certainly 
have  had  an  advantage  over  the  others,  just  because  the 
adaptation  to  the  environment  in  their  descendants  could 
go  on  with  ever  increasing  rapidity. 

"As  modifications  acquired  by  use  during  life,"  writes 
Cope,  "are  necessarily  useful,  it  follows  that  if  one  accepts 
the  post-Darwinian  or  Weismannian  theory  the  only  mode 
of  acquisition  of  useful  variations  which  we  know  is 
excluded  from  the  process  of  organic  development." 

"Each  generation  should  commence,  in  the  matter 
of  useful  characters  acquired  by  use,  at  the  same  point 
at  which  its  ancestors  had  commenced,  so  that  an  accumu- 
lation or  development  of  these  characters  would  hardly 
be  possible.  The  influence  of  the  environment  as  well 
as  the  energies  of  the  living  being  would  be  incapable 
of  developing  in  a  given  generation  more  than  only  that 
which  this  generation  could  acquire  during  its  single  life. 
How  could  evolution,  then,  account  for  the  law,  which 


Inheritance  in  Unicellular  Forms  209 

paleontology  has  demonstrated  in  so  splendid  a  manner, 
of  the  gradual  modification  of  certain  parts  through  long 
geologic  ages  toward  ideals  of  mechanical  perfection, 
for  example,  of  the  gradual  perfecting  of  the  skeletal 
articulations?  Not  only  does  the  post-Darwinian  school 
afford  no  explanation  of  this  but  with  the  acceptance  of 
its  theories  this  progress  is  indeed  impossible."  158 

And  Osborn's  view  is  similar.  "Living  matter," 
writes  he,  "is  characterized  by  a  capacity  of  adaptive  or 
purposeful  reaction.  If  this  capacity  is  inherited  in  the 
Protozoa,  thanks  to  the  simplicity  of  their  process  of 
propagation,  it  must  be  the  same  in  the  Metazoa.  For 
each  newly  developed  metazoon  which  retains  the  advan- 
tage of  the  inheritance  of  the  adaptive  reaction  would 
be  preserved,  while  each  individual  which  loses  this  would 
degenerate.  The  mechanism  of  the  inheritance  of  onto- 
genic  adaptation  must  then  have  been  developed  in 
passing  from  the  unicellular  to  the  pluricellular  forms 
by  means  of  natural  selection."  159 

Weismann  it  seems  to  us  could  reply  only  by  saying 
that  natural  selection  may  not  have  established  the  inher- 
itance of  acquired  characters  in  the  pluricellular  forms 
also,  because  the  production  of  the  mechanism  neces- 
sary for  that  purpose  had  become  materially  impossible 
by  reason  of  the  structure  of  the  metazoic  organism. 
But  this  assertion,  which  would  limit  the  capacities  of 
living  organic  substance,  must  appear  a  little  too  hazard- 

158Cope :  The  mechanical  Causes  of  the  Development  of  the  hard 
Parts  of  the  Mammalia.  Journ.  of  Marph.,  vol.  VIII,  No.  2,  Boston, 
U.  S.  A.  Ginn,  Sept.  1889.  P.  140—141. 

1£8Osborn :  Alte  und  neue  Probleme  der  Phylogenese.  Ergebnisse 
der  Anatomic  und  Entwicklungsgeschichte,  herausgegeben  von  Mer- 
kel  und  Bonnet.  Band.  III.  1893.  Wiesbaden,  Bergmann,  1894, 
P.  607. 


2IO  Inheritance  of  Acquired  Characters 

ous  and  quite  unfounded,  especially  when  one  thinks  that 
apart  from  that  there  is  no  process  or  phenomenon  in 
the  organic  world  which  Weismann  does  not  ascribe  to 
the  almightiness  of  natural  selection.  Thus  the  power 
of  regeneration,  sexual  reproduction,  the  physiological 
necessity  of  death  in  the  pluricellular  forms,  all  are  based 
upon  natural  selection.  And  is  the  almightiness  of  nat- 
ural selection  insufficient  only  for  the  inheritance  of 
acquired  characters? 

After  bringing  to  a  close  this  rapid  review  of  the 
objections  which  Weismann  can  always  oppose  to  any 
argument,  thus  enabling  him  to  save  himself  from  com- 
plete defeat  at  least  with  the  help  of  mere  words  and 
with  a  semblance  of  logic,  it  remains  for  us,  before 
passing  to  the  following  chapter,  to  examine  two  other 
objections  to  his  views  which  seem  to  us  particularly  im- 
portant, in  that  the  arguments  which  he  opposes  to  them 
appear  to  involve  his  own  theory  in  the  most  striking 
contradictions.  These  are  the  inexplicability  of  co- 
ordinated variations,  and  the  repetition  of  phylogeny  by 
ontogeny,  and  with  these  we  shall  close  the  present 
chapter. 

The  objection  to  the  conception  of  the  complete 
sufficiency  of  natural  selection  which  arises  from  co- 
ordinated variations  is  well  known.  When  the  utility 
of  certain  modifications  of  the  organism  depends  upon 
the  correlative  development  of  many  quite  different 
parts  natural  selection  cannot  account  for  the  inter- 
dependent, phylogenetic  modifications,  since,  for  the 
production  of  these  latter,  it  can  act  at  best  only  upon 
special  fortuitous  variations  which  are  independent  of 
others  and  from  that  very  fact  totally  useless. 

Roux  for  example  describes  in  a  masterly  way  the 


Coordinated  Variations  211 

contemporaneous  formation  of  thousands  and  millions 
of  new  characters  each  adapted  to  the  others  and  all 
combined  to  perform  some  function  such  as  must  be 
necessary  in  the  phylogenetic  passage  from  an  aquatic 
to  a  terrestrial  life.  And  he  concludes  in  these  words: 
"One  must  necessarily  conclude  that  functional  adaptation, 
such  as  is  produced  in  alteration  of  the  conditions  of 
life,  can  bring  about  purposeful  co-ordinations  simulta- 
neously in  all  organs  of  the  body  concerned.  And  the 
characteristic  feature  of  this  simultaneity  of  action  in 
millions  of  parts  must  be  the  fact  that  it  is  opposed  to 
the  action  of  natural  selection  which  can  never  develop 
simultaneously  more  than  a  very  limited  number  of 
purposeful  characters."  16° 

Weismann  on  whom  the  force  of  this  objection  aris- 
ing from  correlative  development  is  not  lost,  has  sought 
to  get  around  the  difficulty  by  setting  over  against  it, 
as  we  have  noted  above,  the  neuter  forms  in  bees,  ants, 
and  termites.  He  does  not  deny  the  extraordinary  diffi- 
culty of  explaining  co-ordinated  variations  by  natural 
selection,  but  expects  to  show  that  in  spite  of  it  there 
exist  undoubted  examples  in  which  this  difficulty  was 
overcome  by  natural  selection. 

As  to  the  polemic  which  raged  between  Weismann 
and  Spencer  on  the  subject  of  these  neuters,  we  have 
already  seen  how  in  our  view  Spencer  has  succeeded  in 
driving  his  opponent  from  any  tenable  ground  by 
demonstrating  convincingly  that  the  neuters  are  really 
nothing  else  than  incompletely  developed  females.  We 
shall  not  return  here  to  what  has  already  been  said. 

But  it  is  worth  while  to  observe  that  Weismann  thus 

180Roux:    Der  Kampf  der  Teile  im  Organismus.     P.  39—44. 


212  Inheritance  of  Acquired  Characters 

deprived  of  his  last  stronghold  saw  himself  forced  to 
give  an  explanation  for  these  co-ordinated  variations 
also,  which  should  prove,  at  least  from  a  theoretical 
point  of  view,  that  they  also  might  possibly  be  produced 
through  natural  selection.  But  it  is  just  in  this  attempted 
explanation  that  he  has  fallen  into  the  most  evident 
contradiction,  a  thing  which  was  inevitable  anyway  seeing 
that  his  thesis  is  untenable.  It  is  worth  while  to  spend 
a  little  more  time  examining  this  contradiction. 

He  utilizes  for  this  purpose  a  theory  which,  though 
introduced  only  at  the  last  to  supplement  or  replace  the 
earlier,  already  discussed  theories  of  panmyxia  and  the 
economy  of  the  organism,  was  originally  intended  to 
give  if  possible  some  better  explanation  than  the  earlier 
theories  offered  of  the  continuous  regression  of  useless 
organs  even  after  any  further  regression  is  of  no  more 
value  for  natural  selection.  According  to  this  theory 
when  once  the  involutive  process  has  begun  in  a  given 
organ  from  any  external  provocation  whatever,  it  would 
acquire  in  this  very  way  an  intrinsic  tendency  to  bring 
about  more  and  more  retrogression.  And  the  tendency 
acquired  by  this  organ  and  now  inherent  in  it  toward 
constant  phylogenetic  regression  would  be  accounted  for 
by  the  following  consideration. 

Weismann  affirms  that  when  the  tendency  to  degen- 
erate once  appears  in  an  organ  especially  well  developed, 
let  us  suppose  by  natural  selection,  that  proves  that  it 
is  represented  from  that  time  on  in  the  germ  plasm  by 
determinants  "of  smaller  growing  power."  "But  since," 
he  continues,  "growth  and  assimilation  are  physiologic 
functions,  just  as  are  contraction  and  secretion,  so  the 
fundamental  principle  of  intraselection  is  applicable  to 
them:  the  functional  stimulus  strengthens  the  function- 


"Determinants  of  Smaller  Growing  Power"      213 

ing  organ,  and  the  part  which  performs  its  function 
more  energetically  attracts  to  itself  more  nutrition  and 
repairs  with  interest  its  loss  of  matter  more  rapidly  than 
does  the  part  performing  its  function  less  energetically. 
So  in  the  struggle  of  the  parts  for  nutrition  the  more 
feeble  determinants  will  be  at  a  disadvantage,  they 
become  slowly  but  constantly  feebler  in  the  course  of 
generations  until  finally  they  degenerate  completely."  181 

So  that  according  to  the  view  of  this  investigator: 
"It  is  not  the  functional  change  that  is  inherited;  but 
variations  in  the  biologic  value  of  a  part,  (for  example, 
of  an  organ  which  has  become  useless),  give  the  im- 
pulse to  the  regressive  or  progressive  variations  of  the 
germ  plasm  and  these  only  would  establish  the  heredi- 
tary functional  change  of  the  somatic  part."  162 

Now  it  is  just  this  conception  of  determinants  "of 
smaller  growing  power"  which  is  quite  inadmissible,  and 
which  constitutes  a  contradiction  in  terms. 

For  what  signifies  in  general  "weaker"  or  "stronger" 
determinants?  The  determinants  of  a  small  organ  are 
by  their  very  definition  not  feebler  than  those  of  a  larger 
organ;  they  are  only  qualitatively  different  from  them. 
Also  when  the  variation  of  an  organ  consists  in  a 
diminution  of  its  mass,  this  is  not  a  diminution  of  grow- 
ing power  of  the  respective  determinants  but  an  alteration 
of  these  latter,  which  is  nothing  else  than  their  replace- 
ment by  other  qualitatively  different  determinants. 
Would  Weismann  himself  say  that  the  respective  determi- 
nants of  the  fore  legs  of  the  kangaroo  are  provided  with 
a  smaller  power  of  growth  than  those  of  the  hind  legs? 
Or  that  the  fingers  of  the  human  hand  have  determinants 

161  Weismann  :    Neue  Gedanke  nzur  Vererbungsfrage.    P.  14 — 15. 
182Weismann  :  Ibid.     P.  59. 


214  Inheritance  of  Acquired  Characters 

whose  power  of  growth  stands  in  exact  proportion  with 
their  length?  Would  the  shorter  fingers  therefore  have 
a  phylogenetic  tendency  to  become  constantly  still  shorter, 
and  the  longer  fingers  a  tendency  to  become  steadily 
longer  yet?  If  that  were  so  it  would  lead  directly  into 
this  absurdity,  that  the  formation  in  phylogeny  of  new 
organs  or  of  new  structures  in  general  could  never  have 
any  commencement,  since  originally  their  determinants, 
just  because  of  the  very  smallness  of  these  formations, 
must  have  been  provided  with  only  a  very  small  power 
of  growth  and  therefore  could  never  progress  side  by 
side  with  determinants  which  must  in  any  case  be 
stronger  since  they  belong  to  organs  or  structures  already 
developed. 

If  on  the  contrary  this  is  not  the  case  and  cannot  be 
the  case  because  it  contains  an  unavoidable  contradiction, 
then  the  determinants  of  any  degenerated  organ  what- 
ever, such  for  example  as  the  hind  leg  of  the  immediate 
ancestor  of  the  whale,  cannot  be  regarded  as  feebler,  but 
must  rather  be  regarded  as  qualitatively  different  from 
those  of  the  complete  organ.  Consequently  there  cannot 
exist  for  the  degenerated  organ  any  phylogenetic  tendency 
to  become  still  more  rudimentary. 

Weismann  would  give,  as  we  have  said,  a  quite 
similar  explanation  of  co-ordinated  variations : 

If  there  were,  for  example  an  increase  of  the  weight 
of  the  head,  as  a  direct  result  let  us  suppose  of  natural 
selection,  certain  muscles  of  the  body  after  having 
received  an  initial  impulse  from  natural  selection  itself, 
would  acquire  a  phylogenetic  tendency  to  grow  pari  passu 
with  the  weight  of  the  head.  For  the  first  operation  of 
natural  selection  would  be  to  eliminate  individuals  whose 
muscles  were  too  feeble.  Then  even  if  we  suppose  that 


Weismann's  Explanation  of  Coordinated  Variations  215 

every  fortuitous  variation  that  is  possible,  both  plus  and 
minus,  actually  develops,  the  net  result  after  the  elimi- 
nation of  the  minus  variations  must  be  that  the  muscles 
would  be  stronger.  But  this  initial  increase,  this  first 
impulse  toward  strengthening,  would  be  in  turn  the 
cause  of  a  phylogenetic  tendency  to  a  further  strengthen- 
ing, because  it  would  indicate  that  these  muscles  were 
represented  in  the  germ  plasm  by  determinants  which 
are  endowed  with  a  greater  power  of  growth,  and  con- 
sequently with  greater  power  of  assimilation.  "The 
affluence  of  nutritive  fluids  would  become  proportionally 
augmented  and  would  contribute  likewise  to  giving  the 
plus  variations  a  preponderance  over  minus  variations. 
There  would  thus  be  a  phylogenetic  tendency  toward  the 
continual  increase  of  these  muscles  and  it  would  endure 
just  as  long  as  the  increase  in  the  weight  of  the  head, 
and  would  stop  when  the  latter  stopped.  For  in  this 
case  the  plus  variations  of  the  determinants  would  be 
eliminated  by  individual  selection,  as  soon  as  they 
attained  selectable  value."  163 

But  this  artificially  constructed  hypothesis,  which  did 
not  hold  good  at  all  in  the  case  of  rudimentary  organs, 
is  still  less  adapted  to  the  case  of  co-ordinated  varia- 
tions. For  in  these  phenomena  it  appears  still  more 
clearly  that  in  phylogenetic  changes  there  are  concerned 
not  simply  exclusively  plus  or  minus  variations,  but 
transformations  which  might  be  constituted  by  a  com- 
bination of  increases  in  one  direction  and  decreases  in 
another,  or  might  not  be  susceptible  of  being  decomposed 
into  merely  quantitative  variations.  It  should  be  noted 
further  that  for  certain  correlative,  histological  varia- 

163Weismann :  Neue  Gedanken  zur  Vererbungsfrage.    P.  22. 


2i6  Inheritance  of  Acquired  Characters 

tions  of  physico-chemical  nature,  which  are  concerned 
in  any  way  in  the  fundamental  specific  characters  of 
vital  processes,  the  expressions  increase  and  decrease  have 
no  significance  at  all. 

Nevertheless  it  would  not  have  been  advisable  not 
to  mention  here  these  later  explanations  of  the  atrophy 
of  organs  which  have  become  useless  and  of  co-ordinated 
variations,  because  the  fact  that  Weismann  substituted 
them  for  his  earlier  ones,  shows  that  he  himself  regarded 
the  earlier  explanations  as  insufficient,  and  because  the 
artificiality  of  these  new  explanations  shows  very  clearly 
the  almost  insurmountable  difficulty  encountered  in  the 
attempt  to  explain  these  phylogenetic  phenomena  if  the 
inheritance  of  acquired  characters  is  rejected. 

But  the  phenomenon  which  more  than  any  other 
remains  an  enigma  when  the  inheritance  of  acquired 
characters  is  rejected,  and  which  when  this  inheritance 
is  accepted  becomes  not  only  self  explanatory,  but  sets 
the  whole  mechanism  of  inheritance  in  the  clearest  light, 
is  that  of  the  repetition  of  phylogeny  by  ontogeny,  and 
just  because  of  this  we  reserved  it  for  the  last. 

"Whenever  a  new  species  is  formed/'  writes  Delage, 
"it  is  accomplished  by  the  addition  of  one  or  more  new 
characters,  at  the  end  of  ontogeny,  after  all  the  old 
specific  characters  have  already  appeared.  And  since  this 
goes  on  from  the  very  commencement  it  is  evident  that 
the  characters  must  appear  in  ontogeny,  in  the  same 
sequence  as  in  their  phylogenetic  formation."  164 

But  if  there  is  no  inheritance  of  acquired  characters 
why  should  the  new  character  be  invariably  just  added 
to  those  already  present,  and  only  after  the  development 
of  the  latter  is  completed  ?  Why  should  it  not  be  possible 

le*Delage:  L'heredite  etc.     P.  366. 


New  Characters  in  Phlogeny  217 

for  each  variation  of  the  germ  substance  to  appear  or 
to  become  active,  either  from  the  beginning,  or  at  any 
time  at  all  during  the  ontogeny? 

"The  phenomena  of  latency"  says  Osborn,  "speak 
absolutely  against  Weismann's  conception,  according  to 
which  phylogenetic  development  would  take  place  in  the 
germ  plasm  by  selection  of  advantageous  elements,  and 
elimination  of  disadvantageous  elements.  These  phe- 
nomena of  latency  indicate  that  the  phylogenetic  process 
does  not  consist  in  an  elimination  but  in  a  shoving  of 
certain  characters  into  the  background  (Zurickdrangung) 
during  the  later  stages  of  ontogeny/' 

Osborn  cites  as  example  the  well  known  experi- 
ments of  Cunningham  on  the  color  of  the  asymmetrical 
flat  fishes,  pleuronectids,  on  whose  lower  colorless  side 
artificial  illumination  is  followed  by  a  reappearance  of  the 
pigment  disposed  in  the  same  designs  and  in  the  same 
colors  as  on  the  upper  side,  and  also  Agassiz's  experi- 
ments according  to  which  the  young  of  these  same  fishes 
retain  their  original  symmetry  when  they  are  kept  at  the 
surface  of  the  water  for  a  longer  time  than  under  normal 
conditions.  "According  to  these  experiments,"  Osborn 
says  very  rightly,  "progressive  inheritance  (and  so  phylo- 
geny)  appears  to  represent  rather  a  process  of  substitu- 
tion or  of  addition  than  one  of  true  elimination  in  Weis- 
mann's sense."  165  Thus  these  facts  also  speak  in  favor 
of  the  conception  that  phylogeny  rests  upon  an  addition 
of  new  characters  and  their  superimposition  upon  the  old. 

We  can  see  that  to  explain  by  the  inheritance  of  ac- 
quired characters  this  addition  of  a  new  character  to  the 

16BOsborn:  Alte  und  neue  Probleme  der  Phylogenese.  Ergebn. 
d.  Anat.  u  Entwicklungsgesch.,  herausg.  v.  Merkel  u.  Bonnet.  Bd. 
III.  1893.  Weisbaden,  Bergmann,  1894.  P.  610,  619. 


218  Inheritance  of  Acquired  Characters 

old  only  after  the  completion  of  the  development  of  these 
latter,  it  is  sufficient  to  suppose  that  the  agent  of  trans- 
mission of  an  acquired  character  becomes  active  in  onto- 
geny, only  when  the  young  organism  finds  itself  in  the 
same  conditions  in  which  the  parent  organism  \vas  when 
it  acquired  this  character. 

As  soon  as  one  admits  this  condition  for  the  mech- 
anism of  inheritance  the  law  of  the  repetition  of  phylo- 
geny  by  ontogeny  appears  to  be  merely  the  immediate 
consequence  of  the  inheritance  of  acquired  characters. 

For  so  long  as  the  embryo  is  developing  in  the  egg  or 
in  the  maternal  body  and  so  long  as  it  is  nourished,  sup- 
ported and  protected  by  its  parents,  it  is  withdrawn  from 
the  changing  influences  of  the  environment.  It  is  only 
when  the  individual  is  left  to  himself  that  he  finds  him- 
self driven  perhaps  to  new  functional  adaptations.  In 
other  words  it  is  only  in  the  adult  state,  after  it  has  com- 
pleted or  almost  completed  its  specific  development,  that 
the  organism  in  general  can  find  itself  in  conditions  neces- 
sary for  the  acquisition  of  new  characters. 

But  another  fact  also  can  explain  why  new  phylo- 
genetic  characters  are  acquired  only  when  all  the  old  ones 
are  already  quite  developed.  We  have  indeed  already 
seen  that  the  organism  undergoing  development  is  much 
more  elastic  but  much  less  plastic  than  the  adult,  so  that 
the  modifications  which  arise  in  it  from  the  action  of  an 
external  force,  even  when  it  acts  for  a  long  time,  have 
the  tendency  to  disappear  without  leaving  any  trace  be- 
hind so  long  as  the  organism  has  not  yet  completed  its 
development,  whereas  this  tendency  is  no  longer  inherent 
in  the  adult  organism. 

We  have  already  mentioned  the  experiment  of  Roux, 
in  which  he  distorted  a  few  frog  embryos  within  their 


Inheritance  Explains  Bio  genetic  Law  219 

gelatinous  envelope  by  compressing  them  between  needles : 
"If  the  needles  were  withdrawn  again  immediately  after 
the  deformation,  the  embryo  at  once  resumed  its  earlier 
form.  If  on  the  contrary  they  were  held  in  place  for 
several  hours  the  deformation  became  from  the  first  a 
persistent  one,  and  only  after  several  hours  would  the 
embryos  resume  their  original  form — a  proof  that  an  in- 
ternal adaptation  to  the  new  form  had  already  com- 
menced, but  that  this  adaptation  is  nevertheless  caused  to 
disappear  again  in  the  course  of  further  development,  per- 
haps by  the  action  of  those  very  forces  of  growth  which 
bring  about  the  restoration  of  the  normal  form, 
and  which  were  inhibited  during  the  time  of  the 
deformation."  166 

We  have  thought  it  worth  while  to  mention  again  this 
very  characteristic  example  of  the  elasticity  of  develop- 
ment, because  it,  better  than  others  which  we  have 
already  mentioned  in  the  course  of  our  investigation  of 
the  cause  of  this  elasticity,  helps  us  to  explain  the  rule 
inviolably  followed  in  the  evolution  of  species,  of  the 
addition  of  new  phylogenetic  characters  to  those  already 
present.  For  from  this  it  is  very  evident  that  those 
phylogenetic  characters  whose  appearance  is  caused  dur- 
ing ontogeny  to  some  extent  by  the  action  of  external 
influences,  have  the  tendency  to  disappear  again  promptly 
as  soon  as  the  cause  which  produced  them  has  ceased  to 
act.  So  that,  unless  we  have  an  extraordinary  influence, 
whose  intensity  and  insistent  action  during  ontogeny 
through  the  course  of  successive  generations  give,  it  an 

L68Roux :  Zur  Orientierung  iiber  einige  Probleme  der  embryonalen 
Entwicklung.  Zeitschr.  f.  Biol. ;  Bd.  XXI.  Miinchen.  July  1885. 
P.  515,  516.  Gesamm.  Abhandl.  II.  P.  245. 


220  Inheritance  of  Acquired  Characters 

overmastering  power,  it  will  not  leave  behind  any  trace 
in  the  individual  and  certainly  none  in  the  species. 

Thus  the  inheritance  of  acquired  characters,  thanks 
to  these  two  facts  that  the  embryo  is  usually  withdrawn 
from  the  influence  of  the  environment,  and  that  or- 
ganisms undergoing  development  are  elastic  and  not 
plastic,  shows  itself  to  be  completely  capable  of  account- 
ing for  the  fundamental  biogenetic  law.  Whatever  in  itj 
could  seem  marvelous  and  enigmatic  finds  its  natural  so- 
ultion  and  the  law  itself  becomes  an  immediate  and  neces- 
sary consequence  of  this  inheritance. 

What  on  the  contrary  is  the  explanation  which  Weis- 
mann  is  able  to  give  for  this  law?  He  thinks  to  explain 
it  merely  by  the  following  laconic  words : 

"The  biogenetic  law  rests  upon  this,  that  phylogenetic 
development  is  accomplished  partly  by  the  addition  of 
new  ontogenetic  stages  at  the  end  of  ontogeny.  In  order 
that  this  latter  may  be  attained,  the  preceding  terminal 
stages  must  each  time  be  run  through  again."  167 

But  in  this  Weismann  leaves  just  the  most  important 
part  of  the  question  out  of  consideration.  Why  can 
phylogenetic  development  take  place  only  by  the  addition 
of  new  ontogenetic  stages  at  the  end  of  ontogeny? 

According  to  Weismann's  theory,  there  is  no  reason 
whatever  why  one  should  believe  the  determinants  cor- 
responding to  the  last  ontogenetic  stage  to  be  the  only 
ones  to  undergo  modifications,  for  one  cannot  forget  that 
according  to  this  theory  each  cell  of  each  ontogenetic 
stage  must  have  its  own  determinants.168  The  same 
causes  of  differences  in  the  nutrition  or  any  other  thing, 
which  are  capable  of  modifying  the  determinants  cor- 

167Weismann :  Das  Keimplasma.    P.  no. 
1<58Weismann :    Ibid.,  e.  g.     P.  97,  100,  232—233,  596. 


Weismann's  Theory  Cannot  Explain  Bio  gene  tic  Law  221 

responding  to  the  last  ontogenetic  stage,  must  be  also 
capable  of  transforming  in  the  most  different  ways  the 
determinants  of  the  other  stages.  According  to  that, 
each  phylogenetic  stage  would  have  its  own  ontogeny, 
which  would  differ  completely  even  in  the  first  stages  of 
development  from  the  ontogeneses  of  the  preceding 
phyletic  stages. 

And  there  is  no  more  reason  for  the  supposition  that 
the  only  way  in  which  the  determinants  corresponding  to 
the  last  ontogenetic  stage  could  undergo  modification 
must  be  by  "obtaining  a  greater  power  of  growth,  aug- 
menting consequently  in  number,  differentiating  each  in 
a  new  fashion,  and  adding  thus  at  the  end  of  the  old 
ontogeny  one  or  more  generations  of  cells." 169  For 
these  determinants  could  perhaps  undergo  any  merely 
qualitative  variation  whatever  without  first  augmenting 
in  number,  that  is  to  say  could  become  differentiated  at 
once  in  a  new  way  so  that  the  part  determined  by  them 
should  at  once  take  on  a  form  different  from  the  old  one 
without  needing  first  to  pass  through  its  preceding 
phylogenetic  state. 

We  need  just  to  recall  again  the  example  which  we 
have  already  cited  above,  furnished  by  one  of  the  most 
characteristic  manifestations  of  the  fundamental  bio- 
genetic  law,  namely  ontogenetic  involution,  in  order  to 
demonstrate  in  the  clearest  way  the  absolute  inability  of 
Weismann's  theory,  to  account  for  that  law.  For  accord- 
ing to  that  theory  one  would  understand  for  instance  that 
the  tail  of  the  ancestor  of  the  tadpole,  or  that  the  limbs  of 
the  ancestor  of  the  existing  serpent  may  have  become  con- 
stantly shorter  in  the  course  of  phylogeny  by  virtue  of 

"'Weismann:  Ibid.   P.  no. 


222  Inheritance  of  Acquired  Characters 

natural  selection,  panmixia  or  something  else,  and  that 
consequently  they  have  become  arrested  in  successive 
ontogeneses  at  successively  earlier  stages  of  development. 
But  the  question  cannot  be  repeated  often  enough;  how 
can  this  theory  explain  the  growth  of  these  organs  up  to 
a  certain  stage  of  development  and  their  retrogression 
and  disappearance  in  the  later  stages? 

In  short,  it  seems  to  us  that  one  cannot  imagine  a 
more  complete  overthrow  even  from  a  purely  logical 
point  of  view,  where  it  is  only  a  matter  of  avoiding  con- 
tradiction on  one's  own  premises,  than  thrt  suffered  by 
Weismann  in  the  attempt  to  find  an  explanation  of  the 
repetition  of  phylogeny  by  ontogeny,  and  one  can  hardly 
bring  forward  a  more  thorough  failure  of  a  theory  built 
up  laboriously  with  the  object  of  explaining  all  the  differ- 
ent phenomena  of  heredity,  even  the  most  peculiar  and 
secondary  ones,  than  appears  in  the  fact  that  this  theory 
is  not  even  capable  of  giving  the  least  explanation  of  the 
most  general  biogenetic  phenomenon — the  one  which 
underlies  all  the  others.  And  this  contradiction  and  this 
failure  do  not  appear  so  much  in  the  minute  and  partic- 
ular parts  of  Weismann's  theory,  in  which  it  deals  with 
this  or  that  peculiar  detail,  but  much  rather  in  the  theory 
itself  in  all  its  generality,  which  disputes  the  inheritance 
of  acquired  characters.  Weismann  and  his  supporters 
can,  if  the  most  evident  facts  are  not  enough  for  them, 
deny  this  law  of  recapitulation.  But  that  they  admit  it 
and  nevertheless  dispute  inheritance,  this  is  a  contradic- 
tion from  which  the  opponents  of  the  Lamarckian 
principle  cannot  escape  now  or  ever — a  destructive  rock 

upon  which  all  their  theories  are  wrecked. 

*         *         *         *         *         *         * 

If  now  we  sum  up  succinctly  the  discussion  in  this 


Summary  of  This  Chapter  223 

chapter,  we  are  able  to  affirm  that  although  no  fact  or 
argument  is  capable  by  itself  alone  of  affording  an  ir- 
refutable and  unconditional  proof  either  direct  or  indirect, 
of  the  inheritance  of  acquired  characters,  nevertheless  the 
sum  total  of  the  facts  and  the  arguments  which  are  fa- 
vorable to  it  is  so  weighty  that  one  is  not  only  justified  in 
believing  but  is  even  compelled  to  believe  that  the 
Lamarckian  principle  is  in  all  probability  correct. 

But  the  difficulties  of  explaining  the  mechanism  of 
inheritance  are  so  great,  that  many  investigators  may 
have  thought  them  to  be  insurmountable.  It  is  conceiv- 
able that  many  others,  like  Roux,  have  been  led  to  dis- 
pute its  existence,  just  in  order  to  free  themselves  in  that 
way  from  a  veritable  nightmare.  But  this  position  is  no 
longer  possible. 

The  objective  examination  of  the  question  leads  to 
the  conviction  that  the  inheritance  of  acquired  characters 
is  to  be  considered  as  in  all  probability  a  reality,  there- 
fore we  are  in  duty  bound  to  seek  an  explanation  of  this 
phenomenon  by  some  hypothesis,  even  if  it  be  only  a 
provisional  one. 

So  in  the  following  chapter  we  propose  to  examine 
comparatively  a  few  of  the  most  recent  and  most  im- 
portant hypotheses  which  have  been  devised  for  the 
explanation  of  inheritance.  After  that  in  the  penultimate 
chapter  we  shall  set  forth  more  thoroughly  the  explana- 
tion of  the  Lamarckian  principle  which  the  centro- 
epigenetic  hypothesis  can  give. 


Further  evidence  that  somatic  changes  induced  in  animals  by 
environmental  influences  may  be  repeated  in  their  descendants  as 
a  result  of  germinal  influences  is  furnished  by  Sumner  and  by 
Kammerer.  See  Archiv  fiir  Entwicklungs — Mechanik  der  Organ- 
ismen,  Leipzig,  June  and  September,  1910.  (Translator.) 


CHAPTER  SIX 

THE  MOST  IMPORTANT  OF  THE  EXISTING  BIOGENETIC 
THEORIES  IN  RELATION  TO  THE  INHERITANCE  OF 
ACQUIRED  CHARACTERS. 

We  believe  it  is  unnecessary  to  discuss  here  in  an 
exhaustive  way  the  fact  that  the  question  of  the  admis- 
sibility  or  inadmissibility  of  the  Lamarckian  principle  re- 
mains always  distinct  from,  and  entirely  independent  of 
the  question  of  the  evolutionary  or  epigenetic  nature  of 
development.  Darwin  in  his  evolutionary  theory  with 
preformistic  germs, — a  true  theory  of  preformation, — 
accepts  inheritance ;  Galton  limits  it  to  a  few  cases ;  Weis- 
mann  excludes  it  unconditionally.  Hertwig  accepts  it  in 
his  epigenetic  theory,  although  he  does  not  exclude  some 
sort  of  preformistic  germs;  DeVries  excludes  it.  Roux 
who  was  inclined  at  first  to  believe  that  this  inheritance 
might  exist  in  combination  with  the  chemical  develop- 
ment of  the  egg,  a  theory  frankly  evolutionary  without 
preformistic  germs,  has  finally  regarded  the  two  theories 
as  irreconcilable.  The  only  theories  which  appear  es- 
pecially inclined  toward  the  complete  acceptance  of  the 
Lamarckian  conception,  are  the  epigenetic  theories  with- 
out preformistic  germs,  for  example  that  of  Spencer. 

We  can  now  pass  on  to  the  rapid  review  of  the 
principal  biogenetic  theories  current  today,  with  especial 
reference  to  their  direct  or  indirect  relation  to  the  ques- 

224 


Spencer  225 

tion  of  inheritance  and  to  the  conceptions  of  inheritance 
which  have  been  formed. 

Spencer 

This  author's  idea  of  "physiological  units/'  inter- 
mediate between  the  morphological  units  or  cells  and  the 
chemical  units  or  molecules,  and  representing  the  last 
irreducible  vital  elements,  is  well  known.170 

If  one  supposes  that  in  each  organism  there  exists 
only  a  single  variety  of  these  units,  Spencer  believes  the 
explanation  of  the  inheritance  of  acquired  characters 
would  follow  immediately  from  that. 

"Just  as  the  physiological  units  because  of  their 
special  polarities  build  themselves  into  an  organism  of  a 
special  structure,  so  on  the  other  hand,  if  the  structure  of 
this  organism  is  modified  by  modified  function,  it  will 
impress  some  corresponding  modification  upon  the  struc- 
ture and  polarities  of  its  units.  The  units  and  the 
aggregate  must  act  and  react  on  each  other.  If  nothing 
prevents,  the  units  will  mould  the  aggregate  into  a  form 
which  will  be  in  equilibrium  with  their  pre-existing  polar- 
ities. If  contrariwise  the  aggregate  is  made  by  incident 
actions  to  take  a  new  form,  its  forces  must  tend  to  mould 
the  units  into  harmony  with  this  new  form.  And  to  say 
that  the  physiological  units  are  in  any  degree  so  moulded 
as  to  bring  their  polar  forces  towards  equilibrium  with 
the  forces  of  the  modified  aggregate,  is  to  say  that  when 
separated  in  the  shape  of  reproductive  centers,  these  units 
will  tend  to  build  themselves  up  into  an  aggregate  mod- 
ified in  the  same  direction."  171 

170Spencer :  Principles  of  Biology,  Sixth  edition ;  London,  Will- 
iams and  Norgate.     1898.    Vol.  I.    Chap.  IV,  $66.    P.  224—226. 
171Spencer :  Ibid.   Vol.  I.  Chap.  VIII :  Heredity,  $  84.   P.  319. 


226  Theories  Treating  of  Inheritance 

It  seems  to  us  quite  superfluous  to  expose  any  further 
here  the  pure  verbality  of  such  an  explanation  without 
any  real  content.  Neither  shall  we  go  more  closely  into 
the  objection,  which  is  apparent  on  the  very  surface,  that 
physiological  units  identical  throughout  the  whole  or- 
ganism cannot  form  muscles  here,  bones  there,  nerves 
elsewhere,  all  of  which  represent  special  tissues  with 
totally  different  physical,  chemical  and  vital  properties. 

We  limit  ourselves  rather  to  noting  that,  according  to 
this,  the  inheritability  of  even  quantitative  and  partial 
modifications,  for  example  the  transmission  of  the  merely 
greater  development  of  a  tissue  or  an  organ  already  ex- 
isting, must  be  attributed  to  a  uniform,  qualitative  change 
of  all  the  physiologic  units  of  the  organism.  And  not- 
withstanding that,  the  properties  of  each  group  of  these 
units,  not  excepting  the  group  constituting  the  tissue 
which  has  undergone  a  simple  increase  in  mass,  must  re- 
main identically  the  same  as  they  were  before. 

Let  us  consider  the  case  which  Spencer  himself  quotes 
and  regards  as  one  of  the  examples  of  the  inheritance  of 
acquired  characters,  namely,  the  increase  in  size  or 
greater  development  of  the  great  toe  as  well  as  the 
diminution  or  regression  of  the  little  toe,  as  a  result  of 
the  fact  that  our  ape-like  ancestors  gave  up  life  in  the 
trees  for  life  on  the  surface  of  the  ground.172 

Is  it  possible  that  so  very  local  a  morphologic  change 
has  transformed  qualitatively  the  physiological  units  of 
the  entire  organism?  And  apart  from  the  fact  that  the 
change  is  limited  to  a  certain  very  small  part  of  the  body, 
it  must  yet  be  borne  in  mind  that  one  has  to  do  here  with 
no  new  quality  nor  with  any  new  material  introduced 

172Spencer :  A  Rejoinder  to  Prof.  Weismann.  London,  Williams 
and  Norgate.  1893.  P.  3ff- 


Spencer  227 

into  the  organism  by  the  new  function,  nor  consequently 
with  any  new  physical  or  chemical  or  biological  character 
which  the  organism  has  now  for  the  first  time  acquired; 
but  on  the  contrary  there  is  involved  only  a  different  dis- 
tribution of  already  existing  qualities  of  matter.  But 
how  can  a  change  of  quality  in  imaginary  physiological 
units,  which  would  have  proceeded  uniformly  in  the 
whole  organism,  accord  with  the  fact  that  all  the  qualities 
and  properties  of  this  organism  remain  unaltered,  and 
there  is  merely  another  distribution  of  these  materials? 

Let  us  consider  as  a  further  example  the  instinct  of 
new  born  chickens.  "In  the  first  minutes  of  life,"  writes 
Jastrow,  "chickens  follow  with  their  eyes  the  movements 
of  crawling  insects,  turning  their  heads  with  the  precision 
of  an  old  fowl.  In  from  two  to  fifteen  minutes  they 
pecked  at  some  speck  or  insect,  showing  not  merely  an 
instinctive  perception  of  distance  but  an  original  ability 
to  judge,  to  measure  distance  with  something  like  in- 
fallible accuracy.  A  chicken  hooded  as  it  emerged  from 
the  shell  was  unhooded  when  three  days  old ;  six  minutes 
later  it  followed  with  its  head  and  eyes  the  movements  of 
a  fly  twelve  inches  distant,  and  about  ten  minutes  later 
made  a  vigorous  dart  at  the  fly,  seized  and  swallowed  it 
at  the  first  stroke."  173 

Spencer  would  rightly  attribute  this  instinct  to  the 
long  practice  acquired  by  the  ancestors  of  the  chicken. 
But  if  he  wished  to  explain  this  inheritance  through  the 
alteration  of  specific  physiological  units  of  the  entire 
organism,  such  an  explanation  would  not  be  taken  ser- 
iously. How  could  the  new  physiologic  units,  capable 
of  effecting  this  local  modification  constituted  by  the 

17SJastrow:  The  Problems  of  Comparative  Psychology.  The 
Popular  Science  Monthly.  New-York.  Nov.  1892.  P.  36—37. 


228  Theories  Treating  of  Inheritance 

formation  of  a  few  new  nerve  paths,  at  the  same  time 
reproduce  those  parts  of  the  organism  which  remained 
entirely  unaffected  by  this  local  change  ? 

Finally,  how  can  the  hypothesis  of  Spencer  account 
for  the  law  of  repetition  of  phylogeny  by  ontogeny?  If 
the  explanation  of  the  inheritance  of  acquired  characters 
by  means  of  physiological  units  were  accepted,  this  law 
would  be  futile.  For  the  new  physiologic  units  with 
changed  polarity  must  take  on  at  once  in  the  daughter 
organism  that  form  to  which  the  parent  organism  had 
last  attained,  without  needing  to  pass  first  through  the 
preceding  forms. 

The  physiologic  units  were  devised  in  order  to  permit 
the  comparison  of  the  formation  of  the  organism  with 
that  of  a  crystal.  But  a  substance  which  because  of  a 
slight  qualitative  alteration  of  its  molecules  changes  its 
form  of  crystallization,  goes  over  from  the  very  first 
commencement  of  crystallization  into  a  form  different 
from  the  preceding,  and  takes  on  at  once  the  form  which 
it  will  have  after  the  completion  of  crystallization.  A 
comparison  between  organisms  and  crystals  is  therefore 
inadmissible;  and  this  inability  is  especially  evident  when 
it  is  attempted  in  this  way  to  explain  the  laws  and 
phenomena  of  development,  in  which  organisms  and 
crystals  are  totally  different  and  are  even  antagonistic. 

Haacke 

The  conception  of  Haacke  is  much  like  that  of 
Spencer. 

"According  to  my  view,"  says  he,  "we  have  to  do  not 
only  with  the  genetic  continuity  of  the  germ  cells  of  one 
generation  with  those  of  the  generation  immediately  pre- 
ceding and  following,  but  also  with  a  material  continuity 


Haacke  229 

of  the  germ  cells  with  the  other  cells  of  the  body.  The 
body  represents  a  system  in  equilibrium;  if  this  changes 
the  germ  cells  developing  in  it  change  also.  But  the 
equilibrium  of  the  system  constituted  by  the  body  becomes 
directly  altered  by  the  acquisition  of  new  characters;  con- 
sequently the  changes  which  it  undergoes  must  be  trans- 
mitted also  to  the  germ  cells.  But  no  matter  whether  the 
germ  cells  become  changed  as  a  result  of  the  acquisition 
of  new  characters  by  the  body  which  surrounds  them,  or 
whether  they  remain  unchanged,  they  always  inherit  the 
same  thing,  namely,  the  capacity  to  form  that  body  with 
which  they  were  in  equilibrium."  174 

Like  Spencer  he  supposes  that  this  equilibrium  is  due 
to  the  tendency  possessed  by  an  infinite  number  of  par- 
ticles, identical  throughout  the  whole  organism,  to  dis- 
pose themselves  in  this  way  only.  His  rhomboidal 
geinmes,  grouped  into  composite  units  or  gemmaria,  are 
fundamentally  nothing  else  than  the  physiological  units 
of  Spencer.  The  geometric  form  attributed  to  them, 
which  emphasizes  the  static  character  of  this  explanation, 
does  not  make  it  in  any  way  more  acceptable. 

Nevertheless  there  are  to  be  noted  and  carefully  con- 
sidered, here  perhaps,  even  more  than  in  Spencer,  the 
close  interaction  and  the  reciprocal  equilibrating  influence, 
which  would  always  exist  between  the  soma  and  the  germ 
substance, — that  is  to  say,  between  the  organism  and  that 
small  portion  of  its  units  contained  in  the  reproductive 
cells, — not  only  throughout  the  whole  development  of  the 
individual  but  also  after  the  completion  of  development 
when  the  organism  becomes  subject  to  the  modifications 
which  external  agents  induce  in  it. 

174Haacke:  Kritische  Beitrage  zur  Theorie  der  Vererbung  und 
Formbildung.  Biol.  Centralbl.,  Bd.  XV.  1895.  P.  568. 


230  Theories  Treating  of  Inheritance 

Sedgwick 

This  investigator  deduces  the  possibility  of  the  in- 
heritance of  acquired  characters  from  his  conception  that 
the  pluricellular  organism  is  simply  a  great  syncytium. 

"If  the  protoplasm  of  the  body  is  essentially  a  syncy- 
tium and  the  ovum  until  maturity  a  part  of  that 
syncytium,  the  separation  of  the  generative  products  does 
not  differ  essentially  from  the  internal  gemmation  of  a 
protozoan,  and  the  inheritance  by  the  offspring  of  pecul- 
iarities first  appearing  in  the  parent,  though  not  ex- 
plained, is  rendered  less  mysterious;  for  the  protoplasm 
of  the  whole  body  being  continuous,  we  must  naturally  be 
inclined  to  think  that  every  change  in  the  molecular  con- 
stitution of  any  parts  of  it  would  naturally  be  expected 
to  spread  in  time,  through  the  whole  mass."  175 

This  conception  which  recalls  somewhat  Naegeli's 
idea  of  an  idioplasmic  network,  extending  its  meshes 
throughout  the  whole  body,  though  it  gives  a  hint  of  the 
possible  mechanism  of  inheritance  by  means  of  this  proto- 
plasmic continuity,  nevertheless  does  not  give  even  the 
most  vague  and  remote  notion  of  the  nature  of  this 
mechanism. 

Bard 

According  to  this  author  the  cells  participate  in  onto- 
genetic  development  in  two  ways.  The  first  way  is  by 
their  specific  division  or  qualitative  nuclear  division,  as 
in  Weismann's  theory  of  preformistic  germs.  The  second 
rests  upon  a  special  action  of  the  germ  cells  upon  the 
somatic  cells,  acting  indeed  at  a  distance  but  nevertheless 

175Adam  Sedgwick:  The  Development  of  the  Cape  Species  of 
Pcripatus.  Quart.  Journ.  of  Microscopical  Sc.  Vol.  XXVI.  1886- 
P.  206. 


Bard  231 

not  by  any  mediate  path,  like  the  influence  exerted  by 
electric  induction-currents  in  the  production  of  induced 
currents,  and  Bard  has  therefore  given  this  process  the 
name  of  vital  induction. 

But  this  induction  would  be  exercised  not  merely  by 
the  germ  cells  upon  the  somatic,  but  also  by  the  latter 
upon  the  former.  And  the  modified  soma  is  capable  of 
bringing  about  the  inheritance  of  the  modifications  it  has 
undergone,  by  means  of  an  influence  of  exactly  this  na- 
ture exerted  upon  the  germ  cells  contained  in  it.176 

But  the  inheritance  of  these  new  characters  by  the 
next  succeeding  organism  by  the  means  of  the  germ  cells 
which  give  rise  to  this  latter  can  be  accepted  only  upon 
the  supposition  that  it  is  effected  by  means  of  the  same 
vital  induction  which  had  already  transmitted  the  char- 
acters of  the  paternal  soma  into  the  germ,  now  acting  in 
the  reverse  way.  And  Bard  himself  seems  to  admit  this. 
But  if  this  is  true  for  the  characters  acquired  last,  it  must 
also  be  true  for  all  the  characters  acquired  phylogeneti- 
cally.  Consequently  the  role  which  specific  cell  division 
or  qualitative  nuclear  division  in  the  Weismannian  sense 
would  play  in  the  histologic  differentiation  and  in  the 
whole  development  would  become  reduced  to  nothing. 

We  shall  limit  ourselves  then  to  drawing  attention  to 
the  inconceivability,  made  more  evident  by  the  considera- 
tions just  mentioned,  of  the  idea  that  the  germ  cells  could 
participate  in  the  development  in  two  such  extremely 
different  modes  of  action  simultaneously,  and  the  lack  of 
any  experimental  proof  for  this  supposed  vital  induction. 

176Bard:  Influence  specifique  a  distance  des  elements  celhilaires 
les  uns  sur  les  autres.  Archives  de  Medecine  experimentale ;  i.  serie, 
t.  II.  Paris,  Masson.  May  i,  1890;  and  La  specificite  cellulaire  et  ses 
principales  consequences.  La  Semaine  Medicale.  Paris,  March  10, 
1894. 


2 32  Theories  Treating  of  Inheritance 

Tornier 

Tornier  believes  that  the  nervous  system  acts  as  in- 
termediary, transmitting  the  acquired  characters  from  the 
soma  to  the  germ  cells  and  then  fixing  them  in  the  latter. 

"In  the  more  highly  organized  individuals  each  adapt- 
ation of  the  active  end  organs  is  accompanied  by  a 
corresponding  and  equivalent  adaptation  in  the  central 
nervous  system.  The  central  nervous  system  in  its 
turn  transmits  the  acquired  character  to  the  sexual 
organ  forming  with  it  a  single  functional  and  nutri- 
tive unit,  and  especially  to  the  sexual  cells  causing 
them  to  undergo  an  equivalent  transformation.  When 
the  sexual  cells  become  later  generative  cells,  the  property 
acquired  by  the  parent  is  by  this  means  inherited  by  the 
descendents."  177 

One  does  not  see  nevertheless  how  the  modification 
undergone  by  the  sexual  cells  could  be  reversible ;  that  is 
to  say  how  these  cells  could  produce  in  the  descendants 
the  new  character  which  was  acquired  by  the  parent  or- 
ganism and  to  which  their  own  modification  was  due. 
To  state  it  more  exactly,  one  does  not  see  at  all  how  it 
will  have  satisfied  the  condition  to  which  we  shall  often 
have  occasion  to  return,  and  which  appears  indispensable 
to  this  reversibility,  namely  that  during  ontogeny  there 
is  produced  at  the  right  time  and  the  right  place  an  action, 
which  is  of  exactly  the  same  nature  as  that  by  which  this 
part  of  the  paternal  soma  had  reacted  to  the  modifying 
action  of  external  influences. 

It  is  necessary  nevertheless  to  note  the  important  role 
which  is  thus  attributed  to  the  nervous  system  as  the  in- 

177Tornier:  t)ber  Hyperdaktylie,  Regeneration  und  Vererbung. 
Arch.  f.  Entwicklungsmech.  d.  Org.  Bd.  III.  Heft  4.  and  Bd.  IV. 
Heft  i.  Leipzig,  Engelmann.  1896.  P.  192. 


Hertwig  233 

termediary  through  which  must  pass  all  the  characters 
newly  acquired  by  the  soma  and  thanks  to  which  they 
become  transformed  so  that  they  can  then  be  inherited  by 
following  generations. 

Oscar  Hertwig 

Oscar  Hertwig  gives  in  the  following  words  the  es- 
sentials of  his  theory  of  biogenesis. 

"The  cells,  necessarily  equal  specifically  on  account  of 
their  origin  in  the  segmentation  of  the  egg,  which  are 
combined  to  constitute  an  organic  system  of  a  higher 
order,  have  their  character  determined  by  the  relations  in 
which  they  become  placed  during  the  course  of  develop- 
ment. Their  state  becomes  modified  when  these  relations 
are  modified.  For  the  cell  organism  is  an  extremely  ir- 
ritable substance  so  that  the  slightest  influences  are  suffi- 
cient to  bring  about  modifications  in  it." 

"Contrary  to  the  mosaic  theory  of  Roux  and  the  germ 
plasm  theory  of  Weismann,  the  theory  of  biogenesis  is 
based  upon  the  principle,  that  from  the  commencement  of 
development,  the  cells  arising  from  the  segmentation  of 
the  egg  are  constantly  in  the  most  intimate  relation  with 
one  another,  and  the  character  of  the  developmental  pro- 
cess is  determined  essentially  by  this  fact.  The  cells  do 
not  take  their  especial  future  character  of  their  own  initia- 
tive, but  their  character  becomes  determined  according  to 
laws  which  result  from  the  co-operative*  action  of  all  the 
cells  during  the  successive  stages  of  development  of  the 
entire  organism." 

"The  relations  of  the  rapidly  multiplying  cells  of  the 
substance  capable  of  development  are  constantly  chang- 
ing in  accordance  with  general  laws,  and  the  relations 
between  these  internal  factors  and  thos?  which  are  with- 


234  Theories  Treating  of  Inheritance 

out  the  organism  are  likewise  undergoing  continual 
change,  and  because  of  these  changes  in  relations  new 
conformations  become  produced  at  each  stage  of  the 
developmental  process  in  a  variety  becoming  ever  more 
complex."  178 

Nevertheless  this  does  not  hinder  one,  according  to 
that  investigator,  from  considering  the  organism  in  its 
entirety  as  a  single  physiological  unit  because  of  the  idio- 
plasmic  identity  of  the  nuclei  of  all  its  cells; — a  tiling 
which  he  thinks,  makes  the  inheritance  of  acquired 
characters  conceivable.179 

For  to  explain  the  latter,  Hertwig  brings  up  the  cases 
of  infection,  immunization,  and  other  similar  examples, 
in  relation  to  which  the  organism  can  really  be  regarded 
as  a  single  entity.  He  quotes  for  instance  the  experi- 
ments of  Ehrlich  who  has  succeeded  by  the  administration 
of  extremely  small  doses  of  ricin  in  making  rats  immune 
to  this  poison  which  is  very  powerful  for  them,  and  in 
establishing  the  fact  that  this  immunity  was  acquired  not 
only  by  the  walls  of  the  digestive  canal  with  which  the 
poison  comes  into  immediate  contact,  but  also  by  all  the 
other  tissues  of  the  body,  such  as  for  example  the  sub- 
cutaneous tissues  and  the  ocular  conjunctiva,  and  even 
by  the  germ  cells  as  was  proved  by  the  fact  of  the  trans- 
mission of  this  immunity  to  the  young  born  of  immunized 
parents.180 

Just  as  all  the  cells  of  the  body  are  accessible  to  the 
action  of  ricin  and  thanks  to  that  fact  all  undergo  a 
material  modification,  which  some  of  them,  namely  the 
germ  cells,  transmit  later  to  the  descendants  as  an  im- 

178Oscar  Hertwig,   Die  Zelle  und  die  Gewebe.  II.  P.  75,  144,  T5^ 
179Oscar  Hertwig:  Ibid.  II.  P.  241. 
180Oscar  Hertwijv:  Ibid.  II.  P.  240!?. 
•f 


Hertzvig  235 

munity  against  ricin,  just  so  according  to  Hertwig's  view 
do  all  the  cells  behave  toward  acquired  characters  in  gen- 
eral. "In  the  same  way  as  the  cell  is  sensitive  to  the 
action  of  ricin,  which  brings  about  an  enduring  material 
modification  of  it,  and  this  becomes  inherited  as  im- 
munity to  ricin,  so  I  think  every  cell  is  sensitive  also  to 
the  influence  of  the  general  condition  of  the  body,  which 
brings  about  material  modifications  of  its  substance,  that 
is  of  its  idioplasm  or  hereditary  material,  which  is  es- 
pecially susceptible  of  such  material  modifications,  and 
these  correspond  to  the  cause  as  its  effect  both  in  the  cells 
of  the  soma  and  also  in  the  sexual  products."  181 

We  shall  not  consider  here  the  fact  demonstrated  by 
Ehrlich,  that  in  the  instance  in  which  only  one  of  the 
parents  was  immunized,  the  immunity  was  transmitted 
very  well  to  the  young  of  an  immunized  mother  but  on 
the  contrary  was  not  transmitted  to  the  young  of  an  im- 
munized father;  a  fact  which  seems  to  confirm  the 
hypothesis  of  Ehrlich  that  the  immunity  against  ricin  was 
due  to  the  formation  of  an  anti-ricin,  with  which  the 
protoplasm  of  all  the  cells  became  impregnated,  but  with 
which  the  spermatazoon  could  not  become  impregnated 
because  it  is  almost  entirely  devoid  of  protoplasm,  show- 
ing consequently  that  one  has  to  do  here  not  at  all  with  a 
permanent  modification  of  the  nuclear  idioplasm.  But 
even  apart  from  that  and  even  admitting  the  hypothesis 
that  the  immunity  against  ricin  was  due  from  the  be- 
ginning or  at  the  time  to  the  acquisition  by  the  idioplasm 
of  a  new  and  persistent  character,182  it  is  still  evident 
that  this  is  not  a  just  comparison. 

For  in  the  case  of  infections,  immunizations,  and  so 

181Oscar  Hertwig:  Ibid.  II.  P.  242. 
182Oscar  Hertwig:  Ibid.  P.  241. 


236  Theories  Treating  of  Inheritance 

on,  there  would  be  a  single  identical  influence  exerted 
upon  the  nuclei  of  all  the  cells  without  exception,  which 
makes  it  conceivable  that  thereby  the  special  nuclei  of  the 
different  cells,  and  consequently  of  the  germ  cells  also, 
could  all  inherit  the  new  reactive  property,  which  would 
be  added  to  the  other  special  characters  already  present  in 
each  nucleus  and  different  in  the  different  cells. 

But  in  the  case,  for  instance,  of  a  certain  muscle, 
which  develops  to  a  greater  size  because  of  a  definite 
modification  in  its  local,  trophic,  functional  stimulus,  is  it 
possible  to  make  the  analogous  statement  that  there  is 
thus  obtained  a  new  state  of  the  body  which  brings  about 
a  modification  in  the  idioplasmic  substance  of  all  the  cells 
of  the  organism  without  exception — the  same  modifica- 
tion in  each  of  them  ?  Certainly  this  modification  induced 
in  the  trophic  functional  stimulus  of  a  muscle  and  the 
greater  development  thereby  provoked  in  it  will  exert  an 
influence  on  all  or  nearly  all  parts  of  the  organism;  but 
the  most  probable  supposition  and  that  best  corresponding 
with  the  facts  would  be  that  the  reaction  is  different  in 
each  part.  This  case  at  least  is  quite  different  from  that 
in  which  one  has  to  do  with  the  transmission  of  a  definite 
infection  or  immunity,  and  cannot  be  compared  with  it 
without  further  consideration. 

In  short  Hertwig  supposes  that  every  local  material 
modification  which  appears  at  a  given  point  of  the  idio- 
plasm as  a  reaction  to  a  new  functional  stimulus  extends 
at  once  throughout  the  whole  idioplasm,  so  that  the  latter 
becomes  modified  uniformly  everywhere,  like  a  true 
physiologic  unit : 

"In  the  organism  considered  as  a  physiologic  unit  of 
life  the  actions  of  all  individual  organs,  tissues  and  cells 
must  be  combined  into  a  complex  common  action,  the 


Her  twig  237 

nature  of  which  will  be  conditional  upon  the  general  state 
of  the  organism ;  this  action  will  be  felt  by  each  individual 
part  and  in  so  far  as  it  amounts  to  a  lasting  modification 
of  the  idioplasm  it  becomes  a  newly  acquired  character." 

At  every  fresh  modification  of  the  general  state  of  the 
organism,  "the  total  heritage  of  the  organism  becomes 
enriched  by  a  new  member,  by  a  new  anlage  which  mani- 
fests itself  again  in  the  development  of  the  succeeding 
organism,  in  that  now  the  newly  developing  individual 
reproduces  more  or  less  'from  the  germ  out*  or  from 
internal  causes  the  character  which  its  parents  had  ac- 
quired during  their  lives  from  intercourse  with  the  outer 
world."183 

Does  Hertwig  in  this  say  that  the  reproductive  sub- 
stance is  constituted  by  a  heaping  up  of  a  whole  series  of 
material  modifications,  which  correspond  to  the  successive 
phylogenetic  general  states  of  the  body,  and  constitute  as 
many  potential  tendencies  ? 

That  is  hard  to  decide,  because  all  that  relates  to  his 
conception  of  the  idioplasm  structure  is  obscure  and  often 
contradictory.  Thus  in  some  places  he  seems  to  admit 
that  his  idioplasm  may  be  constituted  by  preformistic 
germs,  so  that  his  theory  would  belong  with  that  of  De 
Vries  to  the  group  of  theories  of  epigenesis  with  pre- 
formistic germs.  In  other  places  on  the  contrary  where 
he  speaks  of  general  states  of  the  idioplasm,  and  other 
similar  things,  every  idea  of  preformistic  germs  seems  to 
be  excluded,  so  that  his  theory  appears  to  be  very  similar 
to  those  of  epigenesis  without  preformistic  germs,  like 
that  of  Spencer.  The  same  is  true  also  of  this  heaping  up 
of  different  material  modifications  representing  the  suc- 

188Oscar  Hertwig:  Ibid.  II.  P.  242,  243. 


238  Theories  Treating  of  Inheritance 

cessive  phylogenclic  states;  he  appears  sometimes  to 
exclude,  sometimes  to  accept  it. 

If  he  accepts  this  heaping  up,  the  explanation  of  the 
inheritance  of  acquired  characters  which  the  hypothesis 
of  biogenesis  could  give  would  be  reduced  to  this : 

The  uniform  modification  into  which  are  summed  up 
during  their  extension  throughout  the  whole  body  the 
different  transformations  in  the  idioplasmic  nuclear  sub- 
stance that  are  brought  about  in  consequence  of  the 
acquisition  of  new  local  characters  is  added  to  the 
preceding  phylogenetic  modifications  without  altering 
them,  but  merely  reducing  them  to  the  potential  state. 
Then  in  the  next  following  ontogeny,  when  the  required 
stage  of  development  is  attained,  and  this  recently  ac- 
quired idioplasmic  modification  becomes  active  in  its  turn, 
it  induces  the  same  general  state  of  the  body  as  was 
induced  in  the  parent  as  a  result  of  the  acquisition  of  new 
local  characters,  and  this  general  state,  because  of  the 
reversibility  of  the  relation  between  action  and  reaction, 
tends  to  bring  about  the  formation  of  this  character  once 
again. 

But  one  must  not  be  deceived  even  by  this.  Even 
supposing  this  to  be  the  explanation  that  the  biogenetic 
hypothesis  could  afford  for  the  inheritance  of  acquired 
characters,  it  would  consist  rather  in  mere  words  than  in 
ideas.  For,  as  we  have  said  above,  this  supposed  summing 
up  of  all  these  different,  simultaneous,  local  variations 
into  a  single  idioplasmic  modification,  including  them  all 
and  uniform  for  the  entire  organism,  lacks  not  only  any 
basis  in  fact  but  also  any  possibility  of  conception.  And 
the  following  questions  remain  unanswered:  In  what 
do  these  different  general  states  of  the  idioplasm  consist  ? 
In  what  way  do  some  come  to  be  added  to  the  others 


Hertzvig  239 

during  ontogeny  one  after  another  in  the  same  order  as 
in  phylogeny?  How  does  each  of  the  successive  general 
states  of  the  idioplasm,  identical  for  the  entire  organism, 
exert  upon  each  individual  cell  so  many  special  actions, 
which  are  not  only  quite  different  from  one  another  but 
also  are  the  exact  reverse  of  those  which  by  their  union 
had  produced  this  general  state  during  phylogeny? 

But  however  that  may  be,  it  is  not  at  all  certain  that 
Hertwig  accepts  this  heaping  up.  For,  as  we  have  said 
above,  if  he  seems  in  certain  places  inclined  to  accept  it, 
he  appears  in  others  to  reject  it  absolutely. 

He  seems  to  accept  it  for  example  when  he  approves 
and  adopts  the  following  passage  from  Nageli : 

"The  unfolding  of  the  anlagen  of  the  idioplasm  fol- 
lows faithfully  the  phylogenetic  order.  While  the  or- 
ganism, developing  in  ontogeny,  runs  successively 
through  the  stages  through  which  its  phylogenetic  stem 
has  run,  the  idioplasmatic  anlagen  become  developed  in 
just  that  order  in  which  they  came  into  existence." 

And  this  conception  appears  confirmed  in  the  follow- 
ing words  of  Hertwig:  "On  account  of  the  progressive 
multiplication  of  the  cells,  their  combined  action  is  con- 
stantly producing  new  embryonic  states  in  the  same  serial 
order  as  that  in  which  they  appeared  during  phylogeny. 
The  individual  cells  are  brought  into  new  relations  to  one 
another  and  to  the  external  world,  and  through  these 
successive  reciprocal  relations  the  anlagen  latent  in  the 
cells  become  awakened."  184 

In  other  places  on  the  contrary  he  seems  to  reject 
completely  this  heaping  up  of  a  whole  series  of  anlagen, 
of  which  each  should  correspond  to  the  phylogenetic  state 

184Oscar  Hertwig:  Die  Zelle  und  die  Gewebe.    II.    P.  251,  253. 


240  Theories  Treating  of  Inheritance 

in  which  it  had  arisen,  and  to  suppose  instead  that  when 
once  the  idioplasm  has  been  modified  there  remains  in  it 
nothing  more  of  the  preceding  states,  not  even  in  a  latent 
or  potential  condition.  At  least  this  would  seem  to  be 
indicated  in  the  following  passages. 

"The  theory  of  biogenesis  makes  it  necessary  for  us 
to  introduce  into  Haeckel's  statement  of  the  fundamental 
biogenetic  law,  a  few  modifications  and  explanatory  addi- 
tions through  which  the  contradiction  (between  this  law 
and  this  theory)  may  be  avoided.  We  should  drop  the 
expression:  repetition  of  the  forms  of  extinct  ancestors, 
and  substitute  for  it:  repetition  of  forms  which  obey  the 
laws  of  organic  development  and  which  progress  from 
the  simple  to  the  complex.  We  should  lay  the  emphasis 
upon  this,  that  in  embryonic  forms,  just  as  in  the  adult 
forms  of  animals,  are  expressed  general  laws  of  develop- 
ment of  organized  living  substance." 

"The  periodically  repeated  development  of  pluricellu- 
lar  individuals  from  unicellular  representatives  of  the 
species,  or  individual  ontogeny,  is  brought  about  in  general 
accordance  with  the  same  rules  as  the  preceding  onto- 
genies, but  becomes  each  time  a  little  modified  correspond- 
ing to  the  extent  to  which  the  characteristic  cell  of  the 
species  was  modified  in  phylogeny." 

"That  certain  conditions  of  form  recur  in  the  develop- 
ment of  animals  with  such  great  constancy,  and  in  the 
main  in  similar  ways,  is  due  chiefly  to  the  fact  that  in  all 
circumstances  they  furnish  the  prerequisite  conditions 
under  which  the  next  later  stages  of  ontogeny  can  be 
produced." 

"The  unicellular  organism,  on  account  of  its  very 
nature,  can  be  transformed  into  a  pluricellular  organism 


Hertwig  241 

only  by  division.  It  follows  that  in  all  living  beings  onto- 
geny must  commence  by  the  cleavage  process." 

"An  organism  constituted  by  layers  and  groups  of 
cells  disposed  in  a  definite  order  can  be  formed  from  a 
heap  of  cells  only  on  condition  that  the  cells  while  they 
are  multiplying,  begin  to  be  arranged  in  separate  assem- 
blages and  so  progress  in  accordance  with  certain  rules 
from  the  very  simple  initial  forms  to  more  complex  ones. 
Thus  the  gastrula  implies  as  prerequisite  the  simpler 
stage  of  the  germinal  vesicle.  Thus  the  embryonic  cells 
must  first  be  disposed  in  germinal  layers,  which  constitute 
the  basis  for  further  processes  of  differentiation  in  their 
territory.  The  anlage  of  an  eye  in  a  vertebrate  can  be 
formed  only  after  a  nerve  tube  has  been  separated  from 
the  outer  germinal  layer,  since  in  it  is  included  also  the 
material  for  the  formation  of  the  optic  vesicles." 

"Certain  forms  then  become  firmly  fixed  in  the 
developmental  process,  despite  all  the  constantly  acting, 
modifying  factors,  because  it  is  only  by  means  of  them 
that  the  complicated  final  state  can  be  reached  in  the  most 
simple  way  and  in  the  most  suitable  manner."  185 

Thus  as  we  said,  Hertwig  seems  in  this  really  to  sup- 
pose, contrary  to  what  he  asserted  above,  that  the  idio- 
plasm is  not  at  all  a  heaping  up  of  numerous  anlagen 
representing  respectively  the  successive  steps  of  the  evolu- 
tion of  the  species,  but  so  transforms  itself  with  each  new 
phyletic  acquisition  that  it  preserves  no  trace  of  preceding 
phyletic  states. 

In  this  he  is  in  complete  accord  with  the  hypothesis 
of  Spencer,  from  which  in  fact  he  quotes  long  passages 
and  makes  them  his  own.  And  accordingly  he  supposes, 

185Oscar  Hertwig:  Die  Zelle  und  die  Gewebe.  II.  P.  273,  274, 
276. 


242  Theories  Treating  of  Inheritance 

as  appears  from  his  own  words  here  quoted,  that  if  the 
organism  appears  to  pass  again  during  ontogeny  through 
the  preceding  phyletic  stages  this  depends  merely  upon 
the  fact  that  there  is  no  other  materially  possible  way  for 
the  idioplasm  to  attain  the  phylogenetic  equilibrium  just 
acquired. 

But  to  accept  this  is  to  deny  the  law  of  repetition. 

One  notes  that  Hertwig  was  lead  to  reject  this  law,  as 
he  himself  admits,  only  because  he  wished  to  avoid  the 
objection  which  Weismann  had  already  urged  against 
Nageli;  namely  that  if  one  supposes  that  different  phylo- 
genetic forms  may  be  due  to  respective  idioplasms  qual- 
itatively different  from  one  another  it  is  not  possible  to 
understand  how  the  same  forms  when  they  succeed  one 
another  in  the  ontogeny  of  a  single  species  can  then 
depend  only  upon  "different  conditions  of  tension  and 
movement,"  of  one  and  the  same  idioplasm. 

But  it  seems  to  us  that  Hertwig  has  attempted  in  vain 
to  circumvent  this  obstacle. 

"A  very  general  and  very  astonishing  fact,"  wrrites 
Delage,  "is  that  ontogeny  almost  never  follows  a  direct 
and  simple  course.  The  cells  almost  never  dispose  them- 
selves from  the  beginning  in  the  order  which  would  bring 
the  embryo  soonest  to  its  final  conformation.  Ontogeny 
approaches  its  goal  gradually,  but  as  though  compelled  to 
tack  against  a  contrary  wind,  and  its  long  tacks  carry  it 
sometimes  far  to  the  side.  It  shapes  a  number  of  rudi- 
ments, permits  purposeless  members  to  arise,  opens  gill 
clefts  in  a  lung  breathing  animal  only  to  close  them  again, 
and  so  on."  186 

These  tacks,  these  deviations  hither  and  thither,  cer- 

18flDelage:  L'heredite  etc.  P.  175—176. 


Driesch  243 

tainly  do  not  denote  any  endeavor  of  the  idioplasmic 
substance  to  proceed  by  the  shortest  route  to  the  condi- 
tion of  its  equilibrium.  They  indicate  that  it  is  quite 
impossible  on  the  one  hand  to  accept  the  passage  of 
ontogenetic  through  phylogenetic  forms  and  on  the  other 
hand  to  refuse  to  this  process  the  significance  of  an  actual 
repetition  of  phylogeny  by  ontogeny.  In  other  words 
one  must  seek  the  cause  of  this  repetition  not  merely  in 
biologic  laws  of  maintenance  of  the  equilibrium  in  an 
existing  homogeneous  idioplasm,  but  chiefly  in  the  entire 
past  of  the  species  and  just  in  the  historic  fact  that  it 
passed  during  its  development  through  such  and  such 
phylogenetic  forms. 

And  so  the  objection  urged  by  Weismann  against 
Nageli  can  be  urged  in  its  full  force  and  even  more  justly 
against  Hertwig.  For  though  Nageli  gave  no  explana- 
tion of  their  causes  and  ways  of  action,  he  nevertheless 
accepted  the  activation  of  a  whole  series  of  different 
anlagen  of  the  idioplasm  in  exactly  the  same  serial  order 
as  in  their  phylogenetic  appearance.  Hertwig  on  the  con- 
trary after  he  had  first  accepted  this  activation  of  succes- 
sive anlagen  of  the  idioplasm  finally  rejected  it. 

Driesch 

This  author's  conception  of  organic  development 
cannot  in  its  very  nature  afford  any  explanation  whatever 
of  the  inheritance  of  acquired  characters  and  conse- 
quently, admitting  that  this  inheritance  exists,  ought  for 
this  very  reason  to  be  considered  inadmissible.  It  can  be 
summed  up  in  the  following  words  of  its  author. 

"Each  cell  concerned  in  the  ontogenesis  in  so  far  as  it 
possesses  a  nucleus  really  carries  within  it  the  sum  total 
of  all  anlagen ;  in  so  far  however  as  it  possesses  a  specific 


244  Theories  Treating  of  Inheritance 

protoplasmic  body  it  is,  just  on  account  of  this  latter, 
susceptible  of  being  acted  upon  by  only  certain  causes 
(causes  which  effect  the  liberation  of  different  individual 
nuclear  energies )." 

"We  believe  that  the  capacity  of  reacting  to  stimuli 
resides  in  the  nucleus,  but  that  the  capacity  of  receiving 
them  resides  in  the  protoplasm,  which  is  chemically 
specific  in  each  elementary  organ.  The  protoplasm  is  thus 
the  medium,  (the  zone  of  perception),  between  the 
liberating  causes  and  the  nucleus,  (the  zone  of  action)." 

"The  appearance  of  elementary  processes  comes  about 
in  each  ontogeny  through  a  liberation  of  potentialities. 
*  *  *  I  break  the  whole  of  ontogeny  up  into  a  series 
of  liberated  effects." 

"Each  liberating  cause  produces  not  only  a  chemical 
specificity  and  thereby  the  new  elementary  process  as  such, 
but  it  produces  through  this  specificity  at  the  same  time 
the  limitation  by  which  the  new  cell  is  capable  of  receiv- 
ing later  only  certain  further  liberating  causes."  18T 

The  especially  striking  thing  in  this  conception  is  the 
absence  of  any  real,  continuous,  reciprocal  dependence  of 
the  different  parts  one.  upon  another  throughout  the 
whole  course  of  development.  Each  cell  will  preserve  in 
its  nucleus,  it  is  true,  the  germinal  substance  uninjured; 
but  the  successive  liberation  of  special  nuclear  energies 
which  will  impart  to  it  its  own  especial  character,  depends 
fundamentally  only  upon  the  specific  properties  which 
its  protoplasm  had  already  acquired  earlier,  and  not  upon 
the  reciprocal  actions  which  exist  between  all  parts  of  the 
body  throughout  the  whole  duration  of  ontogeny,  as  it 
would  according  to  Hertwig's  theory,  for  instance. 

187Driesch:  Analytische  Theorie  der  organischen  Entwicklung. 
P.  81,  49,  60,  82. 


Driesch  245 

For  the  specific  protoplasm  which  a  certain  cell  has 
already  acquired  at  a  given  moment  of  ontogeny  by  re- 
ceiving only  one  certain  stimulus  corresponding  to  its 
immediately  preceding  specificity,  would  really  become 
the  special  cause  by  which  among  all  possible  nuclear 
energies  only  that  one  becomes  liberated  which  should 
become  active  at  that  instant.  The  activation  of  this  new 
nuclear  energy  would  in  its  turn  modify  the  specificity  of 
the  protoplasm  of  this  cell  and  of  its  immediate  descend- 
ants; and  this  protoplasm  so  altered  would  then  become 
the  cause  of  the  reception  of  a  new  specific  stimulus  and 
of  the  consequent  liberation  of  the  next  required  nuclear 
energy ;  and  so  on  up  to  the  completion  of  development. 

Each  cell  of  any  given  ontogenetic  stage  would  thus 
come  to  carry  in  itself  all  that  is  necessary  to  determine 
its  own  future  character  and  that  of  its  most  remote 
descendants,  with  the  exception  of  the  various  stimuli 
which  it  is  the  duty  of  the  protoplasm  to  select  and  to 
receive. 

One  thing  is  not  quite  clear  in  this.  Do  these  liberat- 
ing causes  of  the  different  nuclear  energies,  that  is  these 
stimuli,  among  which  each  protoplasm  should  select  and 
receive  only  those  belonging  to  it,  come  only  from  the 
world  outside  the  organism,  or  also  from  the  reciprocal 
actions  of  the  individual  parts  in  the  interior  of  the 
organism  ?  In  the  first  case  it  would  be  necessary  to  place 
Driesch  among  the  out  and  out  evolutionists;  in  the 
second,  his  theory  would  be  a  mixed  one,  that  is  it  would 
rest  upon  phenomena  of  evolutionistic  nature  combined 
with  others  of  epigenetic  nature. 

We  shall  not  set  forth  any  further  here  what  enor- 
mous difficulties  one  would  encounter  in  either  case  if  one 
sought  to  build  up  in  accordance  with  this  theory  any 


246  Theories  Treating  of  Inheritance 

conception  of  a  mechanism  for  the  inheritance  of  acquired 
characters.  Even  if  the  hereditary  substance  should  be 
preserved  in  its  entirety,  and  unaltered,  in  the  nuclei  of  all 
cells  without  exception  throughout  development,  this 
would  be  ascribable  only  to  qualitatively  equal  nuclear 
division.  But  one  could  not  but  ask  why  the  modifica- 
tions which  supervene  in  the  hereditary  nuclear  substance 
of  such  and  such  somatic  cells  in  consequence  of  a  new 
local  functional  adaptation  in  the  adult  stage  should  not 
remain  limited  to  these  cells  alone. 

Very  noteworthy,  however,  in  Driesch's  theory  is  the 
conception  that  ontogeny  takes  place  by  means  of  a  series 
of  successive  liberations  of  different  energies  remaining 
up  till  then  in  the  potential  state,  and  also  that  one  result 
of  the  liberation  of  each  of  these  energies  and  of  the 
effects  which  it  produces  is  that  the  necessary  and 
sufficient  conditions  for  the  liberation  of  the  next  follow- 
ing potential  energy  are  brought  about. 

Herbst 

The  epigenetic  conception  of  Herbst  is  still  less 
capable  if  possible,  than  that  of  Driesch  of  rendering  con- 
ceivable any  mechanism  whatever  for  the  inheritance  of 
acquired  characters. 

He  mentions  at  first  several  experiments  upon  the 
way  in  which  unicellular  organisms  and  cells  react  to  cer- 
tain stimuli,  and  also  a  great  number  of  facts  serving  to 
show  the  great  dependence  of  plant  ontogenies  especially 
upon  external  influences.  While  it  is  evident  that 
external  influences  constitute  most  often  only  liberating 
or  releasing  stimuli,  they  seem  on  the  contrary  to  become 
in  certain  formations  real  formative  stimuli.  In  these 
formations  there  is  involved  not  only  a  true  ontogenesis 


Herbst  247 

but  an  actual  phylogenesis  which  would  repeat  itself  in 
each  generation  ex  novo,  because  of  the  repetition  always 
in  the  same  way  of  the  same  external  formative  influence. 

After  having  thus  stored  up  a  rich  harvest  of  facts 
upon  the  physiological  actions  exerted  by  the  most  differ- 
ent stimuli  upon  organisms  or  upon  given  parts  of 
organisms, — actions  which  are  properly  nothing  else  than 
functional  adaptations  in  a  broad  sense  of  the  word, — • 
Herbst  believed  he  was  able  to  build  upon  them  his 
epigenetic  conception,  by  which  he  makes  development 
fundamentaly  dependent  upon  a  whole  series  of  directive 
stimuli. 

"Just  as  freely  moving  organisms  are  influenced  in 
the  direction  of  their  movements  by  external  agents,  so 
do  independent  tissue  cells  react  to  definite  directive 
stimuli,  and  thereby  make  possible  the  production  of  a 
large  number  of  ontogenetic  formative  processes." 

"Just  as  the  germinal  vesicles  of  Cuscuta,  for  ex- 
ample, develop  their  stinging  barbs  at  the  points  of 
contact  with  the  plant  upon  which  they  lodge,  just  as  in 
the  leaf  stalks  of  Helleborus  niger  the  traction  of  a  weight 
causes  the  formation  of  new  mechanical  elements  which 
otherwise  do  not  appear,  or  just  as  roots  may  be  made  to 
grow  on  a  grass  stalk  because  of  the  secretion  of  a  gall 
fly,  so,  in  the  interior  of  an  animal  embryo  in  process  of 
development  a  given  organ  can  cause  new  formative  pro- 
cesses to  come  into  existence  in  another  organ  by  means 
of  contact,  pressure,  traction,  by  a  specific  product  of 
metabolism  or  in  some  other  way." 

And  so,  "just  as  in  plants  and  sessile  animals 
morphological  formations  of  the  most  different  kinds  are 
produced  through  formative  stimuli  which  either  arise 
from  the  external  world  or  are  exerted  by  one  organ  of 


248  Theories  Treating  of  Inheritance 

the  organism  upon  another;  so  also  the  morphological 
changes  in  animal  ontogeny  arise  in  the  same  way 
through  manifold  inductive  stimuli  "Inductionsreize" 
which  are  almost  always  of  internal  origin."  188 

This  conception,  especially  if  it  is  extended  to  the 
whole  process  of  development  in  general,  would  really 
amount  to  a  reduction  of  ontogeny,  exactly  as  in  the  plant 
formations  above  mentioned  in  which  external  agents  act 
as  true  formative  stimuli,  almost  to  a  phylogeny,  con- 
stantly repeating  itself  anew  in  each  generation.  And 
the  fact  that  successively  arising  generations  would  in 
spite  of  that  remain  always  alike  is  to  be  attributed  to  the 
repetition,  proceeding  always  in  the  same  way,  of  succes- 
sive functional  stimuli  both  without  and  within  the 
organism  in  process  of  development,  which  are  produced 
gradually  one  out  of  the  other  through  the  principle  of 
fructifying  causality  and  give  rise  each  time  to  these  new 
phylogeneses. 

In  this  respect  the  conception  of  Herbst  recalls  the 
purely  mechanical  explanation  of  development  given  by 
His,  who  refers  the  appearance  of  the  same  ontogenetic 
phenomena  every  time  to  the  repetition  of  definite  me- 
chanical influences,  proceeding  always  in  the  same  way. 
Since  each  influence,  itself  induced  by  the  influences 
preceding  it,  induces  in  its  turn  the  influences  following 
it,  then  if  only  the  first  link  of  the  chain  is  constantly 
repeated  in  the  same  way  in  each  generation,  that  would 
be  enough  to  cause  the  same  thing  to  happen  in  the  case 
of  all  the  others. 

188Herbst :  t)ber  die  Bedeutung  der  Reizphysiologie  fur  die 
kausale  Auffassung  von  Vorgangen  in  der  tierischen  Ontogenese. 
•Biol.  Centralbl.  1894.  Bd.  XIV.  No.  18-22.  P.  77i  J  and  Bd.  XV, 
N.  20—24.  P-  852. 


Herbst  249 

One  notes  that  these  theories  of  Herbst  and  His  and 
other  similar  ones  imply  an  extraordinary  independence 
and  autonomy  even  during  ontogeny  not  only  in  each  part 
of  the  organism  but  even  in  each  cell.  The  development 
of  each  particle,  even  the  most  minute,  would  thus  depend 
fundamentally  upon  the  independence  of  its  response  to 
the  action  of  its  immediate  or  close  environment,  even 
though  this  response  is  given  in  a  very  definite  manner 
and  is  in  no  wise  arbitrary.  But  this  is  hard  to  reconcile 
with  the  mutual  adaptedness  which  there  must  necessarily 
be  between  the  different  parts  constituting  a  single  co- 
ordinated whole.  And  it  is  still  more  irreconcilable  with 
the  constancy  and  precision  with  which  even  the  most 
minute  peculiarities  of  the  organism  are  reproduced  in 
each  development,  even  when  the  conditions  of  the  en- 
vironment in  which  it  takes  place  do  not  always  remain 
alike  in  respect  to  nutrition,  temperature  or  other  factors. 

And  so  much  the  more,  since  the  principle  of  fructify- 
ing causality,  employed  to  explain  this  constancy  and 
rigorous  precision  with  which  the  same  series  of  onto- 
genetic  phenomena  is  always  repeated,  is  a  sword  with 
two  edges.  For,  admitting  that  only  a  single  one  of  the 
numberless  intermediate  links  of  the  chain  should  find 
itself  in  a  somewhat  different  condition  in  relation  to  its 
environment,  or  should  differ  in  any  way  even  though 
inconsiderably  from  the  corresponding  link  of  the  preced- 
ing generation,  a  thing  which  one  might  well  assert  occurs 
in  every  ontogeny,  then  the  remaining  portions  of  the 
chain  would  find  themselves,  because  of  the  modifications 
accumulating  and  multiplying  like  an  avalanche,  altered 
throughout,  and  therefore  in  the  last  links  also.  The 
mutual  adaptedness  of  numberless  different  parts  and 
their  co-ordination  into  a  single  harmonious  whole,  and 


250  Theories  Treating  of  Inheritance 

the  constant  precision  in  the  repetition  even  of  the  most 
minute  peculiarities,  stipulate  fundamentally  an  individual 
ontogenetic  factor,  which  is  directive  and  at  the  same 
time  co-ordinative,  acting  at  each  moment  of  develop- 
ment throughout  the  entire  organism  even  to  the  smallest 
single  parts  of  it.  But  ontogenetic  theories  like  those  of 
Herbst  or  His  take  a  stand  diametrically  opposed  to  this. 

It  is  also  almost  superfluous  to  remark  that  they  cannot 
give  the  least  account  of  the  repetition  of  phylogeny  by 
ontogeny,  and  still  less  of  the  inheritance  of  acquired 
characters. 

For  the  latter,  as  we  can  well  assert  without  needing  to 
fear  that  we  get  too  far  from  the  truth,  requires  ab- 
solutely the  condition,  certainly  not  sufficient,  yet  at  least 
necessary,  that  just  this  ontogenetic  factor  of  individual 
nature  should  act  everywhere  and  incessantly  and  also 
that  it  should  not  give  up  the  control  of  development 
even  for  a  moment,  so  that  it  may  thus  be  in  a  position 
to  experience  in  itself  each  variation  even  the  smallest 
appearing  in  the  organism  in  consequence  of  any  new 
functional  adaptation.  But  the  theories  of  Herbst  and 
His,  and  all  others  like  them,  which  have  recourse  only 
to  the  principle  of  fructifying  causality,  rest  upon  the 
conception  that  the  successive  influences  would  always 
be  left  to  themselves  by  their  respective  special  causes, 
as  soon  as  they  had  once  been  produced  and  launched, 
so  to  speak,  into  development,  to  produce  in  their  turn 
new  influences. 

Therefore  these  theories  necessarily  exclude  any 
inheritance  of  acquired  characters.  But  if  this  latter 
actually  exists  they  become,  as  we  have  said,  quite 
untenable  from  this  point  of  view  also. 


Orr  251 


Orr 


Orr  takes  as  his  starting  point  the  conception  that  he 
has  formed  concerning  the  way  in  which  the  pluricellular 
organisms  arise  from  the  unicellular. 

It  is  easy  to  understand  that  after  the  unicellular 
organism  in  the  course  of  generations  had  attained  a 
certain  size,  its  external  surface  might  have  become 
transformed  in  consequence  of  contact  stimuli  into  a 
denser  protective  layer,  and  thereby  have  lost  its  repro- 
ductive capacity,  which  would  have  been  preserved  only 
in  the  inner  part  of  the  organism. 

"When  such  an  organism  as  this  would  be  divided 
into  a  number  of  pieces  by  the  natural  process  of  repro- 
duction those  parts  of  the  protoplasm  which  had  not 
undergone  a  grosser  material  differentiation  would  be 
like  the  protoplasmic  germs  of  all  its  ancestors,  capable 
of  responding  to  the  same  stimuli,  and  therefore  of  devel- 
oping in  the  same  manner.  The  only  difference  between 
these  and  the  ancestral  germs  would  be  the  increased 
complexity  of  their  nervous  co-ordinations.  But,  on  the 
other  hand,  part  of  the  organism  which  has  been  dif- 
ferentiated into  the  denser  outer  layer  would  be  in 
structure  so  different  from  the  germs  of  the  species  that 
it  would  be  incapable  of  responding  to  any  of  their  accus- 
tomed stimuli  and  therefore  incapable  of  repeating  the 
development." 

"But  at  every  step  in  the  evolution  a  part  of  the 
protoplasm  retains  its  original  qualities,  only  changing 
its  nervous  condition  to  a  condition  of  greater  complexity 
of  co-ordinations.  In  this  way  the  original  protoplasm 
gradually  adds  to  itself  the  co-ordinations  for  developing 


252  Theories  Treating  of  Inheritance 

in  each  generation,  first  cell  walls,  and  then  the  differ- 
entiated organs."  189 

From  the  whole  work  of  Orr  it  seems  to  result  with- 
out any  possible  doubt,  that  according  to  his  view  this 
non-differentiated  part  of  the  protoplasm  is  present  in 
all  the  cells  of  the  organism,  is  everywhere  quite  similar, 
and  is  continuous  to  the  extent  that  stimulating  influ- 
ences can  be  transmitted  from  any  given  part  whatever 
to  all  parts  of  the  animal,  so  that  it  constitutes  a  complete 
physiological  unit.190 

But  on  the  other  hand  it  is  never  to  be  seen  quite 
clearly  what  this  investigator  understands  by  this  greater 
complexity  of  co-ordination.  The  fact  that  the  nervous 
system  presides  over  all  physiologic  activities  of  the 
organism  makes  him  think  rightly  that  development  also 
may  be  dependent  on  similar  nervous  phenomena.  Only 
in  the  nervous  system  of  the  organism  is  clearly  to  be 
seen  what  is  to  be  understood  by  a  greater  complexity 
of  nervous  co-ordinations,  because  it  is  constituted  by 
numberless  points,  distinct  from  one  another  and  con- 
nected with  one  another  in  more  or  less  complicated  ways 
by  direct  or  indirect  nerve  tracts.  In  undifferentiated 
protoplasm  on  the  contrary,  which  remains  always  en- 
tirely similar  in  the  most  different  parts  of  the  body, 
and  a  fortiori  in  that  infinitely  small  part  contained  in 
the  germ  cells,  one  could  not  conceive  in  what  these  sup- 
posed nervous  co-ordinations  and  this  ever  greater  com- 
plexity of  co-ordinations  could  consist,  and  what  their 
significance  would  be. 

The  following  passages  do  not  clear  up  any  of  the 


i89 


9Qrr.     p^  Theory  of  Development  and  Heredity.     New  York, 
Macmillan,  1893.     P.  127—128. 
"°E.  g.  Ibid.    P.  124. 


Orr  253 

obscurity :  "When  we  consider  the  protoplasm's  respon- 
siveness to  stimuli  and  to  the  effects  of  repetition  or  prac- 
tice, with  the  intricate  co-ordinations  that  may  thereby 
be  effected,  also  the  impressions  made  by  stimuli  which 
remain  long  fixed  as  "memory/'  we  are  led  directly  to 
suppose  that  the  property  which  is  the  basis  of  bodily 
development  in  organisms  is  the  same  property  which 
we  recognize  as  the  basis  of  psychic  activity  and  psychic 
development." 

"On  the  same  principle  that  a  thought  in  the  mind 
calls  up  an  associated  thought,  or  one  tone  of  music 
calls  up  another,  or  one  action  in  an  oft  repeated  series 
of  actions  calls  up  the  next  subsequent  action  or  actions, 
so  the  initial  stimulus  being  given  to  an  incipient  organ- 
ism, its  responsive  activity  each  time  tends  to  produce 
by  association  the  next  activity  in  the  oft  repeated  series 
and  so  on  through  the  successive  steps  of  growth  and 
development."  191 

The  points  of  contact  between  the  mnemonic  phenome- 
non of  the  association  or  succession  of  ideas  and  the  phe- 
nomenon of  ontogenetic  development  have  already  been 
very  rightly  brought  forward  by  others  and  we  shall 
return  to  them  for  closer  examination  in  the  last  chapter. 
It  may  be  remarked  here  merely  that  the  first  can  in  no 
way  serve  to  explain  the  second.  For  in  the  first  place 
it  belongs  to  a  class  of  phenomena  still  more  specialized 
and  more  complex  than  the  phenomenon  to  be  explained, 
in  the  second  place  the  conditions  of  origin  and  of  repeti- 
tion are  quite  different  in  the  two  phenomena. 

When  a  melody  strikes  the  ear  for  the  first  time  and 
is  later  often  repeated  it  leaves  behind  impressions  on 

101Orr :    Ibid.     P.  238—239,  142. 


254  Theories  Treating  of  Inheritance 

several  nerve  centers  and  unites  them  by  new  nerve  tracts 
becoming  always  smoother.  These  new  impressions  and 
tracts  remain  then  unaltered  in  the  same  places  in  which 
they  were  produced  and  it  is  just  in  their  continuance 
in  the  place  of  their  origin  that  there  must  be  sought  the 
reason  of  the  always  greater  ease  with  which  these 
melodies  are  reawakened  in  our  memory.  When  the 
muscles  of  the  hand  become  accustomed  to  producing  a 
musical  exercise,  the  greater  development  of  the  muscles 
and  the  greater  complexity  of  the  nervous  co-ordinations 
which  connect  them  with  the  brain  constitute  well  defined 
material  alterations  which  remain  unaltered  in  the  places 
where  they  arise  and  make  the  exercise,  at  first  difficult, 
always  easier. 

In  the  development  of  the  organism  on  the  contrary 
the  causes  of  the  repetition  each  time  of  always  the  same 
ontogenetic  stages  must  reside  in  a  single  cell,  the  germ 
cell.  But  this  cell  is  not  in  any  way  the  place  in  which 
are  produced  the  material  alterations  which  were  acquired 
by  the  parent  organism  and  handed  over  to  the  descend- 
ants, like  the  stronger  development  of  certain  muscles, 
the  greater  complexity  of  certain  nervous  co-ordinations 
and  other  similar  variations.  Of  the  stronger  develop- 
ment of  muscles,  of  the  greater  complexity  of  the  nervous 
co-ordinations  which  are  produced  in  the  parent  organ- 
ism, there  remains  absolutely  nothing,  in  so  far  as  they 
represent  alterations  of  muscles  and  nerves,  in  the  little 
particle  of  matter  which  is  destined  to  produce  the 
descendants. 

Consequently  the  comparison  of  the  two  phenomena, 
although  certainly  very  suggestive,  is  not  sufficient  by 
itself  to  afford  in  any  way  an  explanation  of  ontogenetic 
phenomena. 


Orr  255 

Orr  continues  in  these  words :  "The  co-ordination 
of  forces  which  determines  development  is  not  to  be 
considered  a  definite,  localized  mechanism,  wound  up, 
and  ready  to  go  when  touched.  If  such  were  the  case 
we  ought  to  find  one  such  mechanism  allotted  to  a  cer- 
tain definite  number  of  cells;  but  instead  we  find  that 
each  piece  (of  a  hydra),  regardless  of  the  number  of 
cells,  or  whether  it  be  the  half  or  the  twentieth  of  the 
hydra,  is  capable  of  producing  only  one  new  individual." 

"The  quality  upon  which  development  depends  seems 
to  reside  in  a  small  piece  just  as  well  as  in  a  large  piece 
and  moreover  equally  in  all  parts/' 

"I  think  we  can  best  compare  the  inheritance  of  the 
plan  and  potentiality  of  development  in  the  clump  of 
protoplasm  to  inherence  of  ideas  and  potentialities  of 
volition  in  the  brain  substance,  not  as  though  each  idea 
and  potentiality  were  located  there  in  its  own  minute 
definite  limited  space,  and  attached  to  a  definite  mechan- 
ism of  matter;  but  rather  we  should  think  of  development 
and  mental  potentialities  as  dependent  upon  certain  states 
of  living  matter,  which  states  are  the  result  of  the  entire 
past  history  of  that  living  matter  and  which  thus  deter- 
mine the  method  of  response  to  external  stimuli,  and  the 
direction  which  shall  be  taken  by  the  new  energy  con- 
stantly entering  from  the  outside."  192 

This  recalls  again  the  above  mentioned  conception  of 
Nageli  and  Hertwig  of  idioplasm  which  is  both  general 
and  mnemonic,  with  all  its  short-comings  which  consist 
in  complete  indefiniteness  or  worse  yet  in  lack  of  content 
masked  by  empty  words. 

Nevertheless    it   is    worthy   of    notice   that   however 

192Orr:  Ibid.     P.  172—173. 


256  Theories  Treating  of  Inheritance 

indefinite  the  theory  of  Orr  may  be,  it  contains  a  clearly 
expressed  and  very  remarkable  idea,  namely:  the  con- 
ception that  nervous  activity  is  the  only  general  phe- 
nomenon and  basis  of  life.  Orr  attributes  to  it  therefore 
the  great  function  of  forming  by  itself  the  whole  mechan- 
ism of  development  as  well  as  of  the  inheritance  of 
acquired  characters,  and  seeks  to  explain  through  it  the 
striking  analogy  between  this  mechanism  and  the 
mnemonic  phenomenon. 

Cope 

In  order  to  explain  the  inheritance  of  acquired  char- 
acters Cope  starts  out  with  the  following  investigations 
upon  butterflies.  By  exposing  larvae  which  were  near 
the  stage  of  pupation  to  different  colors,  the  correspond- 
ing colors  were  produced  in  the  chrysalids  developed. 
In  another  experiment  larvae,  which  were  in  the  act  of 
weaving  cocoons,  on  exposure  to  certain  colors  were 
induced  to  weave  cocoons  of  corresponding  colors. 

"In  the  first  experiment/'  explains  Cope,  "the  dynamic 
effect  produced  by  the  exposure  was  stored  for  the  period 
which  elapsed  between  the  exposure  of  the  larva  and 
the  full  development  of  the  pupa.  The  second  experi- 
ment demonstrates  that  a  stimulus  may  be  transmitted 
to  a  gland  so  as  to  modify  the  character  of  its  secretion 
in  a  new  direction.  From  both  experiments  we  learn 
the  transmissibility  of  energy  from  the  point  of  stimulus 
to  a  remote  region  of  the  body,  and  its  conversion  into 
growth  energy  (in  this  case  by  physiogenesis).  This 
prepares  us  to  look  upon  heredity  as  an  allied  phe- 
nomenon, i.  e.  the  transmission  of  a  special  energy  from 
a  point  of  stimulus  to  the  germ  cells,  and  its  compo- 


Cope  257 

sition  there  with  the  ernphytogenic  (inherited)  energy 
into  bathmism  (or  evolutionary  energy)."  193 

From  this  he  at  once  draws  the  conclusion  that  as 
soon  as  a  new  character  is  acquired  by  the  soma  in  con- 
sequence of  a  definite  stimulus,  it  appears  at  the  same 
time  in  the  germ  plasm  also.  This  simultaneous  double 
acquisition  of  the  same  character  by  the  soma  and  by 
the  germ  represents  his  theory  of  "diplogenesis :"  "The 
effects  of  use  and  disuse  are  twofold;  viz.:  the  effect  on 
the  soma  and  the  effect  on  the  germ  plasm.  Those  who 
sustain  the  view  that  acquired  characters  are  inherited 
must  I  believe  understand  it  as  thus  stated.  The  char- 
acter must  be  potentially  acquired  by  the  germ  plasm 
as  well  as  actually  by  the  soma.  Those  who  insist  that 
acquired  characters  are  not  inherited  forget  that  the 
character  acquired  by  the  soma  is  identical  with  that 
acquired  by  the  germ  plasm,  so  that  the  character  acquired 
by  the  former  is  inherited  but  not  directly.  It  is 
acquired  contemporaneously  by  the  germ  plasm  and  in- 
herited from  it.  There  is  then  truth  in  the  two  appar- 
ently opposed  positions,  and  they  appear  to  me  to  be 
harmonized  by  this  theory  of  diplogenesis."  194 

It  is  almost  unnecessary  in  this  connection  to  remark 
that,  if  one  sticks  to  the  letter,  this  supposed  double 
acquisition  of  the  same  character  by  the  soma  and  by 
the  germ,  lacks  any  foundation  in  fact  and  indeed  appears 
inconceivable.  For  in  the  first  place  the  two  experi- 
ments quoted  above  concern  phenomena  too  special,  too 
complex,  and  as  yet  too  little  analysed  to  permit  of 
their  utilization  as  foundations  for  any  theory.  In  the 

193Cope :  The  primary  Factors  of  organic  Evolution.     Chicago. 
The  Open  Court  publishing  Company.    1896.    P.  440. 
194Cope :  Ibid.    P.  442,  443- 


258  Theories  Treating  of  Inheritance 

second  place  if  this  character  instead  of  consisting  in  a 
general  change  existing  in  all  the  cells  concerned,  is 
rather  any  given  local  morphological  or  physiological 
modification  whatever  of  definite  organs  or  tissues,  it 
will  evidently  be  impossible  to  represent  this  modification 
as  acquired  at  the  same  time  also  by  the  germ  plasm, 
since  in  the  latter  these  organs  and  tissues  do  not  exist. 

It  seems  nevertheless  that  Cope's  meaning  is  that 
each  even  local  morphological  or  physiological  modifi- 
cation of  the  soma  must  always  correspond  at  the  same 
time  to  a  certain  specific,  dynamic  state  of  the  proto- 
plasm in  general,  and  that  it  is  this  new  dynamic  state 
which  would  be  acquired  at  the  same  time  by  the  proto- 
plasm of  the  soma  and  by  that  of  the  germ. 

For  to  explain  "the  way  in  which  the  influences  which 
acted  upon  the  general  structure  reach  the  germ  cells," 
he  builds  up  his  "dynamic  theory,"  taken  from  the  do- 
main of  molecular  physics,  and  has  recourse  to  that  spe- 
cial form  of  energy  mentioned  above,  which  he  calls 
"bathmism."  And  this  bathmism  would  consist  acord- 
ing  to  this  author  "in  a  mode  of  motion  of  the  molecules 
of  living  protoplasm  by  which  the  latter  build  tissue  at 
particular  points,  and  do  not  do  so  at  other  points." 

"This  action  is  most  easily  observed  in  the  begin- 
nings of  growth,  as  in  the  segmentation  of  the  oosperm, 
the  formation  of  the  blastodermic  layers,  of  the  gastrula, 
of  the  primitive  groove,  etc.  In  the  meroblastic  embryo 
the  energy  is  evidently  in  excess  at  one  point  of  the 
oosperm  and  in  defect  at  another.  This  is  a  simple 
example  of  the  location  of  growth  force  or  bathmism. 
In  all  folding  or  invagination  there  is  excess  of  growth 
at  the  region  which  becomes  the  convex  space  of  the 
fold;  i.  e.  a  location  or  especial  activity  of  bathmism  at 


Cope  259 

that  point.  All  modifications  of  form  can  thus  be  traced 
to  activity  of  this  energy  at  particular  points." 

"The  building  energy  being  thus  understood  to  be  a 
mode  of  molecular  motion,  we  are  not  at  liberty  to  suppose 
that  its  existence  is  dependent  on  the  dimensions  of  the 
organic  body  which  exhibits  it.  It  is  as  characteristic 
of  the  organic  unit  or  plastidule  as  the  mode  of  motion 
which  builds  the  crystal  is  of  the  simplest  molecular 
aggregate  from  which  the  crystal  arises.  Bathmism  has, 
however,  no  other  resemblance  to  crystalloid  cohesion. 
The  latter  is  a  simple  energy  which  acts  within  geo- 
metrically related  spaces,  without  regard  to  anything 
else  than  the  present  compulsion  of  superior  weight- 
energy.  In  bathmism  we  see  the  resultant  of  innumerable 
antecedent  influences,  which  builds  an  organism  con- 
structed for  adaptation  to  the  varied  and  irregularly 
occuring  contingencies  which  characterize  the  life  of  liv- 
ing beings.  As  this  resultant  is  distinctive  for  every 
species,  bathmism  must  be  regarded  as  a  generic  term, 
and  the  characteristic  growth  energy  of  each  species  as 
distinct  species  of  energy,  which  present  also  diversities 
expressive  of  the  peculiarities  of  individuals."  195 

It  would  be  superfluous  to  bring  forward  the  extraor- 
dinary indefiniteness  and,  we  can  almost  say,  pure 
verbalism  without  any  foundation  in  fact  of  this  theory 
of  Cope's  which  approximates  closely  Haeckel's  theory 
of  perigenesis  with  its  undulatory  plastidular  movement. 
We  shall  confine  ourselves  to  remarking  merely  that  each 
given  dynamic  state  of  the  protoplasm  peculiar  to  a 
given  species,  when  it  thus  represents  in  itself  the  result- 
ant of  all  dynamic  states,  which  were  peculiar  to  the 

19BCope  :    Ibid.     P.  447—449. 


260  Theories  Treating  of  Inheritance 

protoplasm  during  the  whole  course  of  phylogeny,  would 
nevertheless  not  cease  on  that  account  to  constitute  still 
a  special  dynamic  state  which  is  quite  different  from  the 
preceding  ones,  and  which  cannot  possibly  preserve 
materially  even  the  smallest  trace  of  them.  Therefore 
this  theory  of  Cope  leaves  the  repetition  of  phylogeny 
by  ontogeny  quite  as  incomprehensible  as  did  that  of 
Haeckel.  And  on  the  other  hand  one  cannot  see  how 
the  protoplasm  could  be  in  the  same  identical  dynamic 
state  in  all  the  most  different  parts  of  the  soma  and  yet 
give  rise  to  specific  biologic  phenomena  correspondingly 
different  in  each  of  these  parts. 

It  would  have  been  on  the  contrary  a  much  more 
suggestive  idea,  had  Cope  sought  to  reduce  all  the  dif- 
ferent, contemporaneous,  physiological  and  morphological 
variations  of  the  organism,  not  so  much  to  a  single 
and  everywhere  uniform  change  of  this  given  growth 
energy,  as  rather  to  numerous  specific  variations  of  a 
single  generic  form  of  energy,  so  that  the  latter  would 
thus  represent  to  a  certain  extent  the  common  denom- 
inator of  all  these  unlike  morphological  and  physiological 
variations.  For  this  is  in  any  case  one  of  the  means 
which  every  theory  must  employ  which  essays  to  explain 
the  inheritance  of  acquired  characters.  For  when  once 
all  variations  of  the  most  manifold  forms  of  energy, 
acting  simultaneously  upon  the  most  different  points  of 
the  organism,  are  attributed  to  as  many  specific  varia- 
tions of  a  single  form  of  energy  as  the  basis  common 
to  all  of  them,  then  it  would  be  easy  to  combine  with 
it  the  conception  that  for  each  complex  state  of  the 
organism  there  might  appear  in  the  germ  a  single,  well 
defined  specific  mode  of  being  of  this  common  form  of 
energy,  as  the  resultant  of  all  these  specific  different  modes 


Cope  261 

which  are  active  simultaneously,  each  in  its  own  w^ay  in 
the  most  different  points  of  the  soma.  And  just  as  the 
resultant  of  several  forces  acting  upon  one  point  at  the 
same  moment  can  be  decomposed  again  into  its  former 
component  parts,  all  of  which  would  still  act  simulta- 
neously, so  it  is  conceivable  how  this  particular  mode 
of  being  of  the  common  form  of  energy  which  arose 
and  was  stored  up  in  this  way  in  the  germ  can  become 
decomposed  again  at  the  proper  time  at  all  the  various 
points  of  the  new  organism  into  the  same  modes  of  being 
as  formerly,  which  had  already  been  its  components  in 
the  parent  organism. 

To  mitigate  the  fault  of  indefiniteness  in  his  theory 
this  investigator,  just  like  Haeckel,  Orr  and  many  others, 
also  compares  the  ontogeny  thus  produced  by  bathmism 
with  the  mnemonic  phenomenon.  And  although  he  has 
thereby  certainly  neither  removed  or  even  diminished 
the  general  vagueness  which  characterizes  his  whole 
theory  he  succeeds  nevertheless  in  expressing  here  a 
remarkable  and  suggestive  idea. 

"We  may  compare  the  building  of  the  embryo  to 
the  unfolding  of  a  record  or  memory  which  is  stored 
in  the  central  nervous  system  of  the  parent  and  impressed 
in  greater  or  less  part  on  the  germ  plasm  during  its 
construction,  in  the  order  in  which  it  was  stored.  This 
record  may  be  supposed  to  be  woven  into  the  texture 
of  every  organic  cell  and  to  be  destroyed  by  specializa- 
tion in  modified  cells  in  proportion  as  they  are  incapable 
of  reproducing  anything  but  themselves." 

"In  the  case  of  the  germ  plasma  no  other  specialization 
exists  so  that  the  entire  record  may  be  repeated  stage 
after  stage,  thus  producing  the  succession  of  type- 
structures  which  embryology  has  made  familiar  to  us. 


262  Theories  Treating  of  Inheritance 

In  the  process  of  embryonic  growth,  one  mode  of  motion 
would  generate  its  sucessor  in  obedience  to  the  molecular 
structural  record  first  laid  down  in  the  ovum  and  sperma- 
tozooid,  and  then  combined  and  recomposed  on  the  union 
of  the  two  in  the  oospore,  or  fertilized  ovum." 

"Were  all  cells  identical  in  characters,  every  one 
would  retain  the  structural  record  or  memory  of  its  past 
physical  history  as  do  the  unicellular  organisms.  Evolu- 
tion has  however  so  modified  most  of  the  structural 
units  of  the  organic  body  that  none  but  the  nervous 
and  reproductive  cells  retain  this  record  in  greater  or 
less  perfection.  The  nervous  cells  have  been  specialized 
as  the  recipients  of  new  impressions,  and  the  excitors  of 
definite  corresponding  movements  in  the  cells  of  the  re- 
mainder of  the  organism.  The  somatic  cells  retain  only 
the  record  or  memory  of  their  special  function.  On 
the  other  hand  the  reproductive  cells  which  most  nearly 
resemble  the  independent  unicellular  organisms,  retain 
first  the  impression  received  during  their  primitive 
unicellular  ancestral  condition;  and  second,  those  which 
they  have  acquired  through  the  organism  of  which  they 
have  been  and  are  only  a  part."  196 

As  we  shall  devote  ourselves  in  the  last  chapter  to 
the  comparison  of  the  ontogenetic  phenomenon  with  the 
mnemonic,  it  will  suffice  here  to  bring  forward,  as  a 
contradiction  to  the  same  author's  assertion  reported 
above  in  respect  to  a  single  dynamic  mode  in  the  whole 
organism,  the  complete  mnemonic  somatization  of  the 
specialized  somatic  cells,  or  nuclear  somatization,  which 
this  investigator  recognized,  and  also  his  suggestive  sub- 
stantial equalization  of  the  nerve  cells  with  the  repro- 

186Cope:  Ibid.   P.  451—453- 


Delage  263 

ductive  cells  as  the  only  cells  endowed  with  unsomatized 
memory,  and  consequently  as  the  only  ones  which  would 
be  likewise  capable  of  preserving  more  or  less  com- 
pletely the  memory  of  past  generations.  Nevertheless 
he  should  in  our  opinion  have  limited  this  equalization 
with  the  reproductive  cells  to  those  nerve  cells  which 
are  least  differentiated. 

Delage 

According  to  Delage,  "The  egg  is  like  a  star  thrown 
out  by  an  initial  force  into  the  midst  of  a  system  of 
stars  in  movement.  Its  trajectory  will  be  influenced  and 
determined  by  all  the  stars  whose  sphere  of  action  it 
traverses,  but  nevertheless,  if  anything  had  been  altered 
in  its  mass  or  in  its  initial  movement,  it  would  not  have 
been  what  it  is.  It  is  not  dependent  on  the  system  alone 
nor  is  it  at  any  point  independent  of  it.  Every  other 
similar  mass  thrown  out  at  the  same  point,  with  the 
same  force  in  the  same  direction  will  reproduce  a  tra- 
jectory identical  with  its  own;  but  every  difference  even 
the  most  minute,  in  any  one  of  these  three  factors  will 
be  able  to  induce  considerable  differences  in  the  form 
of  this  curve."  197 

This  comparison  leaves  the  repetition  of  phylogeny 
by  ontogeny  and  the  inheritance  of  acquired  characters 
out  of  consideration. 

The  inheritance  of  acquired  characters  is  nevertheless 
accepted  in  part  at  least  by  Delage,  who  explains  it  thus : 
"When  a  new  chemical  compound  introduced  into  the 
organism  produces  different  effects  at  different  points, 
that  is  undoubtedly  due  to  this,  that  it  finds  at  each 

197Delage:  L'heredite  etc.     P.  802—803. 


264  Theories  Treating  of  Inheritance 

individual  point  a  different  cell  substance  as  the  pre- 
dominant element.  Then  if  the  egg  contains  the  sub- 
stance characteristic  of  certain  cells  of  the  organism, 
it  must  be  affected  at  the  same  time  as  these  cells  and 
by  the  same  influences.  According  as  these  influences 
exert  an  exciting  or  depressing  influence  and  so  provoke 
the  corresponding  organ  to  further  development  or  to 
atrophy,  there  will  be  produced  a  similar  action  in  the 
egg,  the  corresponding  substances  will  undergo  a  certain 
growth  or  a  certain  regression  and  when  the  egg  develops, 
the  cells  whose  task  it  is  to  localize  these  substances 
within  them,  will  experience  the  effects  of  this  regression 
or  of  this  growth."  198 

In  the  first  place  it  is  to  be  noted  here  that  the  organs 
whose  modifications  produce  new  phyletic  stages  do  not 
usually  either  develop  or  atrophy  uniformly  in  all  direc- 
tions. Indeed,  specific  morphological  alteration  consists 
rather  in  a  growth  or  diminution  always  proportionally 
unlike  in  different  directions.  The  particular  substance 
which  has  increased  in  the  egg  can  serve  at  most  for 
the  explanation  of  a  quantitative  increase  in  mass  of  the 
organ,  but  not  for  a  morphological  increase,  different  in 
each  different  direction,  like  that  which  the  parent  organ- 
ism has  experienced. 

In  the  second  place  this  explanation  cannot  be  satis- 
factory since  there  may  be  growth  in  one  organ,  while 
another  organ  consisting  of  the  same  tissue,  such  as 
nervous,  muscular,  bony  tissue,  etc.,  may  remain  un- 
changed or  even  regress.  These  organs  consisting  of 
the  same  tissue  ought  all  to  grow  or  diminish  alike  with 

198Delage :  Ibid.    P.  837. 


Delage  265 

each  change  which  their  particular  substance  experiences 
in  the  egg. 

In  the  third  place,  this  would  at  all  events  suffice 
only  for  the  explanation  of  inheritance  of  those  char- 
acters which  develop  in  the  parent  organism  under  the 
influence  of  definite  chemical  actions,  distributed  through- 
out the  wrhole  body,  and  acting  only  upon  those  particles 
or  cells  of  the  body  which  have  a  certain  chemical  com- 
position. But  what  explanation  could  that  give  of  true 
morphological  inheritance  and  so  of  the  inheritability 
of  the  growth  or  of  the  atrophy  of  an  organ  resulting 
from  too  much  or  too  little  use? — of  the  inheritability 
of  the  spongy  structure  of  bone,  of  the  conformation  of 
the  eye,  and  of  all  functional  adaptations  in  general? 

Yet  Delage  gives  the  following  explanation  of  the 
inheritance  of  the  atrophy  of  unused  organs. 

"That  only  is  determined  in  the  egg,  which  is  not 
determined  by  functional  excitation,  but  the  amount 
determined  by  the  latter  is  enormous."  The  absolute 
uselessness  of  slight  reductions  of  the  atrophied  femur 
of  the  whale  and  the  consequent  inefficacy,  in  this  respect, 
of  natural  selection,  and  on  the  other  hand,  the  impos- 
sibility of  understanding  how  the  slight  reduction  in 
volume  which  the  femur  undergoes  during  the  life  of 
the  individual  can  extend  its  influence  to  the  egg,  and 
determine  in  that  the  modification  necessary  for  the 
reproduction,  in  the  following  generations,  of  this  new 
reduction  in  volume,  "forces  us  to  admit,"  continues  the 
author,  "that  neither  in  consequence  of  a  fortuitous 
variation  fixed  by  natural  selection,  nor  in  consequence 
of  an  acquired  and  inherited  modification  does  the  egg 
of  the  existing  whale  differ  in  so  far  as  the  femur  is 
concerned,  from  the  eggs  which  produced  the  whales 


266  Theories  Treating  of  Inheritance 

of  centuries  ago,  whose  femur  was  only  a  very  little 
greater  than  that  of  the  whales  of  today." 

It  still  remains  then  to  explain,  without  devising 
some  improbable  hypothesis,  how  the  same  kind  of  egg 
can  produce  two  different  forms.  And  that  is  not  very 
difficult  when  one  keeps  functional  excitation  in  mind." 

"When  an  animal  has  a  femur  20  cm.  long,  that 
does  not  indicate  that  in  its  egg  all  the  conditions  were 
present  for  the  formation  of  a  bone  of  this  length.  That 
indicates  only  that  the  elements  necessary  for  it  are 
there,  which  with  the  co-operation  of  the  functional 
stimulus  can  form  a  femur  of  such  length.  We  cannot 
know  just  what  part  this  latter  takes  in  the  result,  but 
it  must  be  considerable." 

"While  the  whale  had  still  a  femur,  which  though 
not  normal  was  yet  only  half  atrophied,  the  femur  pro- 
ducing factors  inherent  in  the  egg  were  perhaps  suffi- 
cient to  produce  a  bone  of  only  the  size  of  that  present 
in  the  whales  of  today,  and  the  functional  stimulus, 
which  as  Roux  has  shown,  begins  to  operate  even  in 
embryonal  life,  did  the  rest.  It  is  therefore  not  astonish- 
ing that  upon  the  cessation  of  the  functional  stimulus,  the 
femur  became  reduced  to  a  very  little  rudiment."  199 

But  the  embryonal  functional  stimulus  in  the  whales 
of  many  centuries  ago  whose  femurs  were  only  a  very 
little  bigger  than  those  of  the  whales  of  today,  cannot  have 
been  different  from  the  embryonal  functional  stimulus 
of  the  whales  of  today,  no  matter  how  much  one  may 
limit  direct  morphological  action  of  the  egg,  if  one  starts 
out  from  the  hypothesis  that  the  eggs  concerned  are  quite 
identical.  Why  should  the  embryonal  functional  stimu- 

"'Delage :    Ibid.    P.  854—85?. 


Delage  267 

lus  in  respect  to  the  useless  femur,  already  so  atrophied, 
have  been  greater  in  the  former  than  in  the  latter?  The 
progressive  diminution  of  the  femur  remains  thus  entirely 
unexplained. 

Finally  Delage  accounts  for  the  parallelism  between 
ontogeny  and  phylogeny  in  the  following  way: 

"The  functional  stimulus  appears,  we  agree  with 
Roux,  even  in  embryonal  life,  but  is  at  this  time  certainly 
weaker  than  after  birth.  There  results  from  that  a  note- 
worthy consequence  which  escaped  Roux.  That  is  that 
at  least  the  relative  atrophy  of  the  organ  becomes  more 
marked  the  older  the  animal  becomes,  and  that,  in  respect 
to  the  atrophied  organ,  the  young,  and  above  all  the 
embryo,  must  differ  much  less  from  the  ancestral  forms. 
Thus  there  is  explained  at  once  the  parallelism  between 
ontogeny  and  phylogeny  in  everything  which  is  depend- 
ent upon  atrophy  or  hypertrophy  induced  by  use  or  dis- 
use, that  is  in  very  many  cases."  20° 

Is  it  inactivity  that  really  causes  in  serpents  the  retro- 
gression during  embryonal  life  of  the  already  partially 
developed  limbs?  Or  is  it  use  that  in  the  salamanders 
causes  to  any  extent  the  development,  during  embryonal 
life,  of  the  same  limbs  ?  Whence  come  these  very  unlike 
embryonal  processes  of  activity  or  inactivity?  Why  did 
not  this  same  inactivity,  consequently  this  same  atrophy, 
show  itself  in  the  embryos  of  the  remote  ancestors  of 
the  serpents  of  today?  Why  does  the  inactivity  and 
consequently  the  atrophy  of  these  extremities  depend, 
in  the  egg  of  the  present  day  serpents,  upon  conditions 
within  the  embryonic  organism  itself,  and  manifest  itself 
at  exactly  that  ontogenetic  moment,  which  corresponds 

200Delage :    Ibid.     P.  856—857. 


268  Theories  Treating  of  Inheritance 

to  the  phylogenetic  moment  at  which  it  was  produced 
in  their  ancestors,  whereas  in  the  latter  this  reaction 
commenced  only  when  the  animal  was  exposed,  after 
leaving  the  egg,  to  the  influences  of  the  external  world, 
and  was  rendered  necessary  only  in  consequence  of  very 
definite  circumstances  external  to  the  organism?  We 
see  thus  that  the  question  of  the  repetition  of  phylogeny 
by  ontogeny  finds  no  answer  at  all.  It  seems  to  us 
further  that  there  remains  only  the  erroneous  view  that 
entire  phylogenetic  epochs  could  have  gone  by,  without 
leaving  behind  any  trace  in  the  egg,  so  that  the  progress 
of  each  ontogeny  would  be  nothing  else  than  a  phylogeny 
which  is  almost  entirely  repeated  each  time. 

In  the  second  edition  of  his  work  Delage  recognized 
himself  that  the  significance  attributed  by  him  to  the 
functional  stimulus  in  ontogeny  is  exaggerated.201  And 
he  admits  that  he  was  embarrassed  in  explaining  by 
it  both  the  special  fact  of  the  formation  of  an  organ  so 
complicated  and  so  well  adapted  to  its  purpose  as  the 
eye,  for  which  during  embryonal  life  there  was  never- 
theless lacking  any  functional  stimulus,  and  also  the 
phenomena  of  regeneration,  or  the  general  fact  that 
nearly  all  organs  without  exception  show,  from  the  first 
stages  of  their  development  on,  an  adaptation  to  the  func- 
tions which  they  will  perform  only  later.202 

LeDantec 

According  to  LeDantec's  theory,  each  individual, 
living,  elementary  mass  or  plastid  "contains  a  mixture 
of  different  plastic  substances,  which  are  distributed  in 
such  a  way  that  assimilation  represented  by  the  equation : 

201Delage:   Ibid.   P.   862.   Remark. 
802Delage :  Ibid.    P.  870. 


Le  Dantec  269 

a  +  Q  =  X  a  +  R  (where  a  =  mass  of  each  single 
specific  assimilating  substance;  Q  =  mass  of  the  nutritive 
substances  absorbed ;  x  =  coefficient  >  i ;  and  R  =  mass 
of  the  substances  of  refuse),  multiplies  all  these  sub- 
stances and  preserves  to  them  their  original  proportions. 
Destruction  however,  or  at  least  certain  destructions,  act 
separately  on  each  of  these  substances  and  alter  the  pro- 
portions of  the  mixture  and  consequently  the  characters 
of  the  plastid."  203 

From  this  it  appears  that  LeDantec  attributes  all 
variations  which  the  plastids  or  organisms  in  general 
can  undergo,  to  total  or  partial  destructions  of  the  dif- 
ferent, particular  plastic  substances  (a)  already  present, 
but  never  to  the  production  of  new  plastic  substances. 
The  numbers  and  characters  of  plastic  substances,  which 
participate  in  the  formation  of  the  complex  substance 
of  the  plastid  or  rather  of  the  organism  in  general,  may 
be  different  in  different  species.  The  difference  between 
different  species  and  between  different  individuals  of  the 
same  species,  would  consist  only  in  the  proportions  in 
which  the  special  plastic  substances  (a)  peculiar  to  this 
species,  are  united. 

"We  are  inclined  to  regard  the  living  substances  of 
the  plastids  as  mixtures  of  different  plastic  substances, 
the  substances  (a).  The  species  of  the  plastids  would 
be  determined  by  the  nature  or  quality  of  these  plastic 
substances;  their  individual  peculiarities,  their  person- 
ality, would  depend  upon  the  proportions  of  the  mixture  of 
these  specific  plastic  substances.  In  the  same  way  we  must 
regard  the  individual  substances  in  the  higher  organisms 
as  characterized  by  a  mixture  in  definite  proportions  of 

MiLe  Dantec:  Traite  de  Biologic.    P.  93. 


270  Theories  Treating  of  Inheritance 

the  living  substances  characteristic  of  their  species.  We 
are  able  in  this  way  to  present  even  a  mathematical  defini- 
tion of  the  personality  of  a  given  individual  of  a  species, 
to  a  certain  extent  an  arithmetical  personal  description 
of  this  individual,  namely  the  list  of  co-efficients  of  the 
mixture  of  his  specific  substances."  204 

The  proportions  of  this  mixture  persist  unaltered  in 
all  cells  of  the  same  organism.  Upon  this  mixture 
depends  the  quality  of  the  chemical  reactions,  i.  e.  of  the 
molecular  movements;  upon  these  latter  again  depend 
the  molar  movements  or  osmotic  currents  of  nutritive  and 
excretive  material;  upon  the  molar  movement  finally 
depends  the  form  of  each  plastid  as  well  as  that  of  the 
most  complicated  organism: 

"It  is  absolutely  useless  to  suppose,  in  the  egg  which 
produces  man,  other  characters  present  than  for  example 
those  of  a  simple  hepatic  or  epithelial  assimilative  ele- 
ment, determining  by  this  assimilation  the  molar  move- 
ments around  it.  These  molar  movements  associated 
with  the  movements  which  result  from  assimilation  in 
neighboring  elements,  and  also  with  the  existence  of  the 
skeleton  such  as  is  constituted  in  a  thenceforth  unchange- 
able form  from  the  moment  of  its  first  anlage,  determine 
the  conditions  of  local  equilibrium  from  which  the  local 
form  of  the  body  results.  Analogously  as  soon  as  a 
human  element  (the  fecundated  egg)  is  capable  of  liv- 
ing by  itself  alone,  the  molar  movements,  which  assimila- 
tion provokes  first  in  this  element  alone  and  later  in  all 
which  are  derived  from  it,  determine  the  successive 
forms  of  the  growing  mass  arising  from  assimilation. 
The  phenomenon  appears  from  the  outside  then  to  be 

204  Le  Dantec :  Ibid.     P.  267. 


Le  Dantec  271 

quite  otherwise  than  as  though  this  element  had  assimi- 
lated without  being  isolated,  as  though  for  example  it 
had  belonged  to  a  man  in  process  of  growth.  It  would 
then  have  been  the  destiny  of  this  element,  thanks  to 
the  combined  "dynamisms"  of  the  neighboring  elements, 
to  build  up  a  part  of  the  man,  but  not  a  whole  man."  205 

Finally  the  transformations  to  which  the  living  sub- 
stance would  be  forced  by  the  constraint  of  external 
influences  may  be  hereditary,  i.  e.  can  take  place  anew 
in  the  descendant  organism  without  any  further  need  of 
the  action  of  the  same  constraint,  because  they  would 
alter  the  living  substance  itself  in  a  corresponding  way, 
so  that  it  adapts  itself  to  the  new  conditions  of 
equilibrium : 

"If  assimilation  were  the  only  possible  phenomenon 
of  living  matter  there  would  not  take  place  any  alteration 
of  the  living  substance  through  external  influences;  but 
upon  the  truly  vital  phenomena  of  assimilation  are  super- 
imposed as  we  have  seen  phenomena  of  destruction,  and 
the  co-operation  of  these  two  phenomena  can  result  in 
changes  in  the  nature  of  the  substance,  in  the  definite 
proportions  of  the  mixture  forming  it;  thus  education 
can  modify  heredity." 

"Since  the  form  is  the  result  of  the  molar  move- 
ments of  the  metabolism  of  all  cells  of  the  body,  a 
variation  imposed  on  the  form  reacts  upon  these  molar 
movements  by  which  again  the  molecular  movements  in 
the  interior  of  the  cell  are  determined.  Then  in  con- 
sequence of  this  form  imposed  on  the  body  mass,  there 
will  occur  within  the  cells  phenomena  of  destruction, 
i.  e.,  of  variation.  The  variations  may  take  any  direction 

206  Le  Dantec :  Ibid.    P.  257—258. 


272  Theories  Treating  of  Inheritance 

whatever;  but  natural  selection  (which  acts  in  each  cell 
of  the  organism  among  the  different  plastidular  varia- 
tions) intervenes  and  fixes  only  those  which  are  adapted 
to  the  new  conditions  of  equilibrium."  206 

We  would  just  remark  here,  that  the  alteration 
undergone  by  the  molar  movements  within  each  cell  will 
be  different  in  the  different  cells.  For  it  would  be  incom- 
prehensible how  in  the  very  complex  structure  of  the 
organism,  a  local  change  of  form,  imposed  by  external 
agents,  could  induce  quite  identical  alterations  in  the 
molar  movements  of  all  the  other  cells  of  the  body 
indiscriminately.  Consequently  the  alterations  of  the  liv- 
ing substance  which  internal  natural  selection  preserves 
as  fittest  will  likewise  be  different  in  different  cells.  How 
then  can  there  be  any  question  of  the  survival,  in  con- 
sequence of  this  internal  natural  selection,  of  one  single 
plastidular  variation  identical  at  all  points  of  the 
organism  ? 

LeDantec,  like  Hertwig,  has  recourse  to  the  example 
of  immunization.  But  as  we  have  already  seen,  this 
case  is  quite  different  from  the  more  or  less  local  changes 
of  form,  which  individuals  experience  in  consequence  of 
particular  functional  adaptations.  In  the  case  of  immuni- 
zation the  transforming  cause,  i.  e.  antibacterion,  is  the 
same  for  all  cells.  In  the  case  of  a  morphological 
alteration  on  the  contrary  the  transforming  cause,  that 
is,  as  we  would  concede  it,  the  variation  experienced  by 
the  molar  movement  concerned,  is  different  in  each  cell. 

Even  if  one  were  willing  to  assume  an  identical 
variation  of  the  living  substance  at  all  points  of  the 
organism  indiscriminately,  that  would  not  explain  the 

80aLe  Dantec :   Ibid.    P.  270,  298. 


Le  Dantec  273 

law  of  the  repetition  of  phylogeny  by  ontogeny,  as  we 
have  already  had  occasion  to  remark  in  connection  with 
the  similar  hypotheses  of  Spencer,  Hertwig  and  several 
others.  This  requires,  as  we  have  seen,  the  conception 
of  the  addition  of  a  new  substance  to  all  those  formerly 
present. 

All  variations  of  the  organism  are  ascribed  by 
LeDantec,  as  we  have  already  seen,  to  total  or  partial 
destruction  of  some  of  the  different  plastic  substances 
(a),  which  make  up  the  living  substance,  whereby  their 
quantitative  proportions  become  changed;  but  never  to 
the  formation  of  new  plastic  substances.  Likewise  dif- 
ferent species  would  differ  from  one  another  in  the 
number  and  quality  of  the  plastic  substances  (a).  From 
this  it  follows:  i,  that  no  further  development  can  be 
effected  by  any  given  living  matter,  if  the  number  of 
its  substances  has  become  very  small,  and  thus  an  abso- 
lute inalterability  must  be  established  as  soon  as  this 
number  is  reduced  to  one;  2,  that  the  development  of 
the  species  can  have  been  produced  only  by  successive 
total  destructions  of  an  always  greater  number  of  these 
plastic  substances;  3,  that  the  further  a  species  is  devel- 
oped, the  smaller  therefore  must  be  the  number  of  the 
plastic  substances  which  form  its  respective  living  matter. 
One  would  thus  arrive  at  the  absurdity,  that  the  simpler 
the  living  substance  is  the  more  complex  must  be  the 
organisms  formed  from  it. 

Finally  LeDantec,  like  Spencer,  Hertwig  and  the 
others  is  unable  to  explain  histological  differentiation  by 
this  supposed  similarity  of  living  substance  in  all  parts 
of  the  organism : 

"A  muscular  element  differs  entirely  from  a  nervous 
epithelial  element,  and  these  differences  are  manifested 


274  Theories  Treating  of  Inheritance 

not  only  in  the  form  of  cells  but  also  in  their  mode  of 
activity.  Now  what  is  the  nature  of  these  differences? 
We  do  not  know.  Are  they  physical  in  character? 
That  would  be  hard  to  believe,  because  of  the  difference 
of  the  chemical  excreta  of  these  elements.  If  the  dif- 
ferences are  of  chemical  nature  they  must  leave  uninjured 
the  hereditary  patrimony  (the  living  substance  similar 
at  all  points  of  the  organism).  Now  it  is  entirely  impos- 
sible that  quantitative  variations  can  be  produced  in  the 
elements,  and  leave  untouched  a  quantitative  character 
already  present.  Perhaps  there  is  properly  speaking  no 
quantitative  variation,  but  only  a  modification  in  the 
nature  of  the  non-living  accessory  substances  which  fill 
out  the  aggregate  at  different  points  of  the  organism 
according  to  the  special  conditions  obtaining  at  these 
points.  To  all  these  questions  we  have  as  yet  no 
answer."  207 

Before  we  leave  this  investigator  we  must  bring  up 
one  last  point,  namely :  the  logical  necessity  which  forces 
him  to  regard  the  living  substance  as  similar  at  all  points 
of  the  organism.  According  to  him,  this  conception  is 
a  logical  consequence  of  the  inheritance  of  acquired 
characters  which  he  holds  as  a  fact  already  proved 
beyond  a  doubt.  For,  says  he,  let  us  consider  any  given 
morphological  variation  acquired  by  the  organism  and 
transmissible  to  its  descendant.  And  let  us  assume  that 
the  hereditary  patrimony,  i.  e.  the  living  substance  (  «  ) , 
originally  common  to  all  elements  of  the  individual  by 
descent  from  the  egg,  can,  under  the  influence  of  the 
morphological  variation  experienced  by  the  latter,  have 
been  replaced,  here  by  a  different  substance  (  p  ) ,  there 

207Le  Dantec :  Ibid.     P.  461—462. 


Le  Dantec  275 

by  another  substance  (  y  )  and  so  on,  in  such  a  way 
that  the  whole  of  the  "dynamism"  existing  in  this  hetero- 
geneous mass,  finds  its  expression  in  a  form  of  equili- 
brium F,  which  preserves  accurately,  without  any  need 
of  further  constraint,  those  forms  of  equilibrium  which 
the  individual  had  acquired  in  consequence  of  the  com- 
pulsion of  external  influences. 

"If  that  were  so,"  continues  LeDantec,  "this  form 
could  not  be  hereditary.  For  the  substance  ft  produces 
the  form  F  only  with  the  assistance  of  cells  of  the  sub- 
stances 7  and  8  ,  which  are  simultaneously  present  in 
other  elements  of  the  altered  individual,  and  no  one  of 
these  substances  which  does  not  belong  to  the  sum  total 
of  the  elements  is  by  itself  a  consequence  of  the  total 
form  F.  If  then  one  detaches  from  this  form  a  few 
pieces  capable  of  reproducing  themselves,  these  pieces 
endowed  with  different  substances  or  heritages  will  give 
rise  to  different  individuals,  namely  to  individuals  or 
groups  of  cells  like  those  whose  total  constituted  the 
form  F,  but  of  which  none  had  this  form.  There  is  thus 
absolutely  no  reason  existing  why  any  one  of  these 
individuals  should  take  the  form  F.  If  then  observation 
teaches  us  that  acquired  characters  can  be  inherited  we 
are  thus  obliged  to  suppose  that  in  _  the  case  in  which 
they  are  hereditary  they  were  acquired  by  the  parent 
organism  in  a  homogeneous  manner."  208 

Thus  if  it  were  possible  to  explain  this  inheritance 
and  at  the  same  time  to  accept,  nevertheless,  the  most 
complete  diversity  of  the  substances  constituting  individ- 
ual parts  of  the  organism,  LeDantec  would  be  perhaps 
the  first  to  renounce  with  joy  his  single  individual  sub- 

208Le  Dantec :    Ibid.    P.  294—295. 


276  Theories  Treating  of  Inheritance 

stance,  similar  throughout  the  whole  organism,  which 
as  he  himself  states,  makes  histological  differentiation  at 
least  inexplicable. 


THEORIES    OF    CHEMICAL    DEVELOPMENT 

In  his  fundamental  work  "The  Struggle  of  the  Parts 
of  the  Organism,"  and  therefore  at  a  time,  before  Roux 
had  yet  reached  the  preformistic  view  of  idioplasm  or 
germ  plasm  which  he  later  very  clearly  adopted,  and 
which  in  many  respects  is  like  the  conception  of  Weis- 
mann;  when  also  he  still  considered  development  to  be 
rather  the  complex  result  of  a  long  series  of  purely 
chemical  phenomena,  and  nevertheless  had  not  yet  wel- 
comed Weismann's  theory  of  the  non-inheritance  of 
acquired  characters  as  a  deliverance  from  a  nightmare, 
at  that  time  he  sought  to  explain  this  inheritance  in  the 
following  way: 

First  he  notes  that  the  germ  plasm  although  it  be- 
comes separated  at  the  very  commencement  of  develop- 
ment from  the  organism  in  process  of  formation, 
"remains  nevertheless  dependent  upon  and  in  relation 
with  this  organism;  for  it  must  be  fed  and  grow  and 
multiply  and  to  that  end  it  receives  its  nourishment  from 
its  parent  by  chemical  metabolism,  and  might  still  be 
influenced  in  its  own  nature  in  this  way."  209 

He  supposes  further  that  on  the  one  hand  each 
structural  formation  may  be  conditioned  by  certain  spe- 
cial, chemical  relations,  and  vice  versa  that  each  variation 
of  form  which  the  adult  organism  undergoes  through 
functional  adaptation  produces  in  its  turn  a  certain 

M9Roux:  Der  Kampf  der  Teile  im  Organismus.    P.  60. 


Theories  of  Ciiemical  Development  277 

special  chemical  change.  This  chemical  change  would 
later  become  transmitted  to  the  germ  plasm  by  means 
of  the  metabolism.210 

One  can  not  rightly  comprehend  here,  how  a  special 
chemical  modification,  produced  in  the  germ  plasm  by 
a  change  of  form  in  the  adult  organism,  can  later  give 
rise  to  such  a  development  by  that  germ  plasm  as  to 
reproduce  the  same  change  of  form  at  the  proper  time 
in  the  new  organism.  If  the  chemical  variation  cor- 
responding to  a  definite  change  of  form  were  provoked 
by  the  germ  plasm  in  the  new  organism  only  at  the 
time  when  this  latter  reached  the  same  age  and  conse- 
quently a  state  of  being  which  would  be  the  same  in  its 
entirety  as  that  of  the  parent  organism  when  this  given 
variation  of  form  supervened  in  it,  and  were  confined 
to  the  same  limited  zone  in  which  this  chemical  variation 
was  produced  in  that  parent  organism,  then  the  concep- 
tion of  an  actual  reversibility  of  the  phenomena  would 
not  be  in  itself  at  all  impossible,  that  is  it  would  not  be 
impossible  that  the  same  chemical  phenomenon  might 
provoke  in  the  new  organism  the  same  variation  of  form 
by  which  it  had  itself  been  produced  in  the  parent  organ- 
ism. But  in  our  case  on  the  contrary  this  chemical  varia- 
tion, no  matter  whether  it  transforms  the  whole  chemical 
composition  of  the  germ  plasm  or  only  a  part,  will  com- 
mence to  act  upon  the  new  organism  immediately,  at  the 
very  commencement  of  its  development,  and  will  modify 
therefore  not  merely  a  limited  part  of  the  cells  of  the 
organism,  but  all  the  cells  without  exception.  How  then 
could  this  same  chemical  change,  which  operates  immedi- 
ately at  the  commencement  of  development  and  conse- 

210Roux  :  Ibid.   P.  61. 


278  Theories  Treating  of  Inheritance 

quently  upon  all  stages  of  development  and  upon  all 
cells  of  the  organism,  call  forth  the  same  result  as 
if  it  had  come  to  act  upon  only  a  very  definite  point  and 
at  a  very  definite  time  of  the  development  of  this  organ- 
ism? It  seems  to  us  that  we  ought  much  rather  to 
conclude  that  these  results  must  be  very  different  and 
that  with  them  there  can  be  no  question  of  any  similarity 
whatever. 

This  impossibility  of  explaining  the  inheritance  of 
acquired  characters  by  Roux's  earlier  theory  is  not  limited 
to  it  alone,  but  pertains  to  all  theories  of  chemical  develop- 
ment in  general.  And  the  fault  lies  not  only  in  the  above 
mentioned  impossibility  of  the  reversibility  of  the 
phenomena  of  inheritance  which  we  have  just  considered 
but  also  in  a  still  more  generally  characteristic  circum- 
stance, which  is  likewise  common  to  all  these  theories  of 
chemical  development,  and  which  we  have  elsewhere 
already  stated  for  other  theories.  And  it  is  mostly  from 
it  that  this  impossibility  of  reversibility  comes.  It  con- 
sists in  this,  that  according  to  all  of  these  theories  as  soon 
as  the  germinal  substance  has  once  given  the  initial 
impulse  to  development  it  is  unable  to  exercise  even  the 
slightest  influence  upon  the  further  course  of  this  develop- 
ment. If  thus  the  reins  by  which  development  is  directed 
are  let  fall,  and  each  bond  severed  which  connects  the 
changes  of  the  soma  with  those  of  the  germ  and  vice 
versa,  then  it  is  impossible  to  conceive  how  this  union 
could  later  be  re-established,  as  soon  as  the  need  was  felt 
of  transmitting  to  the  germ  and  fixing  in  it  the  requisite 
variation,  corresponding  to  that  which  appeared  in  the 
soma  as  the  result  of  a  new  functional  adaptation. 

Hofmeister's  theory  can  be  considered  as  an  especially 
typical  example  of  this  complete  abandonment  of  develop- 


Theories  of  Chemical  Development  279 

mcnt  to  itself,  which  constitutes  the  great  defect  of  all 
theories  of  chemical  development. 

This  investigator  believes  that  the  chemical  activity 
of  the  cell  is  due  in  general  to  colloidal  ferments  which 
are  contained  within  them  and  of  which  each  is  destined 
for  a  special  chemical  process.  He  admits  thereby  the 
existence  of  numerous  colloidal  ferments  in  cells  with 
multiple  chemical  processes,  and  he  sees  in  ontogeny  the 
result  of  a  series  of  chemical  reactions  which  follow  one 
another  according  to  the  principle  of  fructifying 
causality : 

"During  the  development  of  the  embryo  there  takes 
place  a  chemical  differentiation  parallel  with  the  morpho- 
logical differentiation.  The  formation  of  new  chemical 
anlagen  indicates  the  appearance  of  different  ferments  at 
definite  stages  of  embryonal  development." — "One  could 
hardly  form  a  better  idea  of  the  chemical  transformations 
going  on  during  the  early  development  of  the  embryo 
than  by  supposing  that  at  first  only  a  very  small  number 
of  ferments  become  active,  and  that  these  transform 
existing  material  into  new  substance,  among  which  pro- 
ferments  or  ferments  of  another  kind  appear,  through 
which  the  first  then  become  annihilated,  and  which 
become  supplanted  in  their  turn  by  a  new  generation  of 
ferments  which  they  have  themselves  produced  and  so  on 
until  the  cycle  of  new  chemical  formations  requisite  for 
the  history  of  the  race  is  run  through.  The  epigenesis  of 
form  would  be  then  only  the  expression  of  the  epigenesis 
of  chemical  forces."211 

We  shall  pass  over  the  fact  that  all  these  theories  of 
chemical  development  have  yet  to  explain  the  connection 

J11Hofmeister :  La  chimie  de  la  cellule.  Revue  generate  des 
sciences;  Aug.  15,  1902.  P.  730—731. 


280  Theories  Treating  of  Inheritance 

between  each  chemical  and  the  corresponding  morpho- 
logical stage  of  development;  for  this  morphological 
character  of  different  chemical  reactions  has  not  so  far 
been  observed  in  any  phenomena  of  the  inorganic  world, 
since  it  has  absolutely  no  analogue  in  the  process  of 
crystallization  which  is  a  property  of  the  molecular  struc- 
ture of  already  formed,  stable  substances,  that  is  of 
substances  in  perfect  statico-chemical  equilibrium.  But 
we  may  mention  the  fact — and  after  all  which  has  been 
said  above  no  further  proof  of  it  is  required — that  the 
fundamental  phenomena,  such  as  the  regeneration  of 
amputated  organs,  the  occasional  reappearance  especially 
in  crosses  of  atavistic  characters  long  since  disappeared, 
and  especially  the  ontogenetic  repetition  of  phylogeny 
and  the  inheritance  of  acquired  characters,  not  only  find 
no  explanation  in  all  these  hypotheses  of  chemical 
development  but  are  on  the  contrary  absolutely  irrecon- 
cilable with  them. 

Darwin,  Gait  on,  DeVries,  IVeismann 

It  would  be  useless  for  our  purpose  to  tarry  especially 
over  any  one  of  these  four  theories,  the  underlying  idea 
of  all  being  the  same  identical  conception  of  preformistic 
germs.  The  progressive  elaboration  of  this  idea  which 
has  proceeded  gradually  from  the  first  to  the  last  of  these 
theories  presents  however  the  following  noteworthy 
phenomenon.  Preformistic  germs,  which  were  devised 
by  Darwin,  one  could  well  say,  chiefly  for  the  purpose  of 
accounting  for  the  inheritance  of  acquired  characters, 
were  then  deprived  by  Galton  in  great  part  but  not  com- 
pletely of  this  property,  and  finally  with  DeVries,  and 
still  more  with  Weismann  became  themselves  the  greatest 
difficulty  for  accepting  that  inheritance. 


Darwin  28 1 

Of  Darwin's  pangenesis  it  is  necessary  here  to  men- 
tion only  the  conception  that  the  sexual  or  reproductive 
organs  in  general  were  not  so  much  the  place  of  refuge  to 
which  the  germ  plasm  withdrew  immediately  after  its 
separation  from  the  soma  at  the  very  commencement  of 
development,  as  rather  the  containers  of  the  germinal 
substance  continually  produced  and  secreted  by  other 
parts  of  the  organism  lying  without  these  organs,  so  that 
they  build  up  as  it  were  the  sexual  or  reproductive 
cells  out  of  this  valuable  material  thus  received  and 
accumulated.212 

In  Darwin's  hypothesis  this  conception  of  the  repro- 
ductive organs  as  mere  glands  for  the  reception  and 
giving  up  again  of  the  germinal  substance  was  intimately 
associated,  although  in  its  essence  quite  separate  and 
independent,  with  his  further  conception  of  the  free 
circulation  of  the  gemmules  throughout  the  organism; 
and  he  supposes,  as  is  known,  that  these  gemmules  were 
produced  and  secreted  continuously  during  the  adult  state 
by  all  somatic  cells  indiscriminately, — by  those  already 
present  as  well  as  by  those  just  appearing  in  consequence 
of  a  new  functional  adaptation.  Now  if  Galton  by  his 
experiments  on  the  transfusion  of  blood  from  a  rabbit  of 
one  species  to  the  blood  vessels  of  another  belonging  to  a 
related  species,  has  provoked  a  thoroughly  justifiable 
doubt  of  this  supposed  circulation  of  gemmules,  especially 
in  so  far  as  it  was  carried  on  in  the  blood  vessels,  the 
original  idea  remained  nevertheless  unshaken,  that  is  that 
the  germinal  substance  is  assembled  in  the  sexual  glands 
after  it  has  been  formed  in  some  real  place  of  origin 
external  to  them. 

212Darwin :  The  Variation  of  Animals  and  Plants  under  Domesti- 
cation. II.  P.  370,  379. 


282  Theories  Treating  of  Inheritance 

Because  of  the  fact  that  the  theory  of  Darwin  derives 
the  germinal  substance  from  all  parts  of  the  soma  rather 
than  from  one  well  defined  region  of  it,  its  partisans 
could  certainly  not  object  to  these  experiments  that  they 
leave  the  conception  still  possible  that  the  germinal  sub- 
stance might  perhaps  be  transmitted  from  such  a  special 
well  defined  region  to  the  sexual  organs  only  along  certain 
very  definite  special  ways,  which  might  be  quite  different 
from  the  blood  vessels.  And  on  account  of  the  nature  and 
properties  attributed  to  the  gemmules  they  would  be  still 
less  able  to  advance  the  conjecture  that  a  substance  might 
possibly  be  reproduced  at  a  distance,  quite  like  another 
substance,  by  the  direct  influence  of  the  latter,  by  means 
of  some  other  means  of  connection  of  such  nature  that 
it  would  not  require  any  real  and  proper  material  trans- 
mission. From  this  the  conclusion  may  be  drawn,  that 
all  theories  which  do  not  exclude  or  perhaps  even  include 
one  or  the  other  of  these  two  hypotheses  upon  the  manner 
of  transmission  or  upon  the  means  of  reproduction  at  a 
distance  of  the  germinal  substance,  are  completely  justi- 
fied in  accepting  Darwin's  conception  of  the  sexual 
glands,  acording  to  which  the  latter  have  only  the  func- 
tion of  receiving  and  accumulating  a  substance  the  real 
origin  of  which  is  outside  these  organs. 

In  the  case  of  Galton  we  shall  recall  only  that  he  was 
the  first  who  introduced  the  theory  that  stirp, — i.  e.,  the 
germ  plasm  consisting  of  numerous  germs  or  of  gem- 
mules  which  remain  behind  after  the  extrusion  of  the 
particles  concerned  directly  in  the  formation  of  the  new 
organism — separated  itself  entirely  from  the  soma 
immediately,  at  the  commencement  of  development. 
Through  this  separation  of  the  stirp  from  the  soma  he 
opened  the  \vay  which  later  led  necessarily  to  the  uncon- 


Gallon;  DeVries;  Weismann  283 

ditional  rejection  of  the  inheritance  of  acquired  char- 
acters. Nevertheless  he  did  not  immediately  venture  to 
go  so  far  but  continued  to  admit  as  a  sort  of  concession 
that  in  the  adult  organism  a  gemmule  might  occasionally 
escape  from  the  somatic  cell,  which  had  produced  it  and 
was  also  its  customary  abode,  even  though  this  cell  had 
been  only  shortly  before  acquired  in  consequence  of  a  new 
functional  adaptation ;  then  this  gemmule  might  be  taken 
up  by  the  reproductive  organs  and  become  likewise  a  part 
of  the  stirp  and  the  acquired  character  which  had  ap- 
peared in  the  somatic  cells  might  thus  be  inherited.213 

In  the  case  of  DeVries  we  should  remark  that  he 
assumes  that  the  germinal  substance,  that  is  the  sum  total 
of  the  pangens,  is  present  equally  in  all  nuclei  only  be- 
cause he,  as  we  have  also  seen  in  the  case  of  Driesch,  took 
it  for  granted  that  nuclear  divisions  are  qualitatively 
equal.  If  then  a  nucleus  of  a  somatic  cell  acquired  new 
pangens,  as  a  consequence  of  a  new  local  functional 
adaptation,  then  they  would  have  to  remain  in  the  place 
where  they  arose  and  could  not  enter  the  reproductive 
cells  also.  And  so  much  the  more  since  he  also  asserts 
that  the  substance  which  will  later  actually  form  the 
sexual  cells  separate  itself  from  the  soma  immediately,  at 
the  commencement  of  development,  and  passes  along  cer- 
tain "Keimbahnen,"  which  may  be  recognized,  chiefly 
because  upon  them  the  greater  part  of  the  pangens  remain 
inactive.214 

In  respect  to  Weismann  we  remark  once  again  that  in 
consequence  of  a  more  rigorous  logical  elaboration  of  the 
doctrine  of  preformistic  germs,  which  has  convinced  him 

213Galton:  A  Theory  of  Heredity.  Journ.  of  the  Anthropo- 
logical Institute.  January  1876.  P.  342—343. 

"4De  Vries:     Intracellulare  Pangenesis.     P.  188—189. 


284  Theories  Treating  of  Inheritance 

of  the  necessity  of  regarding  them  as  bound  up  with  one 
another  into  a  rigid  structure,  he  has  been  led,  through 
the  conception  of  these  preformistic  germs  which  was 
forced  upon  him  by  particulate  inheritance,  to  deny  most 
energetically  every  possibility  of  the  inheritance  by  the 
germ  of  characters  which  the  soma  had  acquired  by 
functional  adaptation. 

Weismann  admits,  it  is  true,  that  sometimes  external 
influences  acting  uniformly  upon  the  whole  organism,  like 
temperature  and  other  such  things,  can  alter  the  deter- 
minants of  the  soma  and  the  corresponding  determinants 
of  the  germ  at  the  same  time  and  in  the  same  direction; 
as  occurs  for  example  in  the  determinants  of  the  wing 
scales  of  the  butterfly  Polyommatus  phlaeas,  whose  color 
changes  as  we  have  seen  when  it  is  transported  to  a 
warmer  climate.  But  the  cases  which  permit  of  this  ex- 
planation, which  resembles  in  many  respects  the  above 
discussed  diplogenesis  of  Cope, — the  only  cases  which 
Weismann  admits, — are  limited  by  this  investigator  to  so 
small  a  number,  and  are  also  of  so  peculiar  a  kind  that  it 
would  be  wrong  to  assert  that  he  held  less  determinedly 
to  his  earlier  stand  as  an  opponent  of  the  Lamarckian 
theory. 

We  may  point  out  however,  the  following  contradic- 
tions. He  admits  inheritance  in  unicellular  organisms 
while  he  denies  it  in  the  pluricellular  and  thinks  he  can 
justify  this  by  saying  simply  that  as  the  unicellular  divide 
always  into  two  equal  halves  they  need  only  preserve 
what  they  have  acquired,  in  order  to  transmit  it  unaltered 
to  the  new  individuals.  But  this  is  not  right.  For  new 
functional  adaptations  acquired  by  the  anterior  end  of  the 
infusorian  Stentor,  for  instance  the  acquisition  of  "Mem- 
branelles"  by  the  peristome  in  consequence  of  the  fusion 


Weismann 


285 


of  several  cilia,  would  then  become  transmitted  only  to 
that  one  of  the  two  new  individuals  to  which  the  anterior 
part  falls  in  the  division,  and  could  in  no  wise  be  trans- 
mitted to  the  other  individual  in  which  this  anterior  part 
is  formed  anew.  If  one  assumes  on  the  contrary,  that 
transmission  goes  on  by  means  of  the  nuclei,  and  can 
therefore  proceed  equally  into  both  of  the  two  newly 
forming  individuals,  one  could  not  then  understand, 
wherein  the  transmission  of  somatic  modifications  in  the 
unicellular  animals,  which  is  accomplished  by  means  of  a 
part  of  the  organism  containing  in  itself  no  membranelles 
and  quite  distinct  from  them,  would  differ  from  the  trans- 
mission of  any  modification  experienced  by  any  organ  of 
a  pluricellular  organism,  which  likewise  goes  on  by  means 
of  a  fragment  containing  no  part  of  the  modified  organ 
and  quite  distinct  from  it.  So  much  the  more  since  the 
substantial  identity  of  the  complex  unicellular  with  the 
pluricellular  organisms,  which  we  have  already  discussed 
above,  corresponds  also  with  a  substantial  identity  in  their 
development,  as  is  shown  by  the  fact  that  the  funda- 
mental biogenetic  law  of  the  repetition  of  phylogeny  by 
ontogeny  is  followed  in  the  development  of  unicellular 
animals  also,  as  for  example,  in  the  formation  of  the  new 
frontal  field  in  the  division  of  Stentor  coereleus.215 

And  in  relation  to  all  these  theories  with  preformistic 
germs  from  Darwin  to  Weismann  we  might  mention 
once  more  the  insurmountable  difficulties  that  would  be 
encountered  if  one  were  required  to  explain  by  them  this 
very  fundamental  law,  either  in  unicellular  or  pluricellu- 
lar organisms.  This  impossibility  and  the  fact  that  in  the 

215Johnson:  A  contribution  to  the  Morphology  and  Biology  of 
the  Stentors.  Journ.  of  Morphol. ;  vol.  VIII,  No.  3,  Boston,  U.  S.  A., 
Ginn,  August  1893.  P.  519. 


286  Theories  Treating  of  Inheritance 

end  the  acceptance  of  these  germs  has  led  necessarily  to 
systems  which  reject  the  inheritance  of  acquired  char- 
acters concur  to  prove,  although  more  proof  is  certainly 
no  longer  necessary  after  all  the  other  considerations 
which  we  have  developed  in  an  earlier  chapter,  that  the 
very  idea  of  these  preformistic  germs  is  untenable,  as  is 
thus  every  theory  founded  upon  them. 


However  limited  the  number  of  theories  or  hypoth- 
eses selected  by  us,  and  however  rapid  and  brief  the 
critical  exposition  which  we  have  made  of  them,  it  seems 
to  us  nevertheless  that  it  is  unnecessary  to  proceed  further 
with  our  examination.  For  it  has  shown  us  that  among 
the  principal  theories,  which  up  to  the  present  have  been 
devised  to  explain  the  inheritance  of  acquired  characters, 
none  has  accomplished  this  difficult  task,  and  it  has 
already  served  another  purpose  for  which  chiefly  we 
undertook  it.  This  purpose  consisted  on  the  one  hand  in 
bringing  to  light  in  other  theories  the  most  suggestive  and 
fruitful  ideas  put  forward;  on  the  other  hand  in  deter- 
mining the  conditions  which  are  necessary  and  sufficient 
to  render  possible  the  inheritance  of  acquired  characters, 
and  a  critical  examination  of  concrete  theories  already 
developed  has  certainly  helped  to  put  these  conditions  in 
evidence  better  than  simple  reflection  upon  them  could 
have  done. 

If  we  take  a  look  over  the  road  which  we  have  thus  far 
traveled  we  see  that  among  these  conditions  those  which 
have  appeared  to  us  as  the  essential  and  fundamental  ones 
are  the  three  following: 

i.  All  the  manifold  physical,  chemical,  morphologi- 
cal, and  physiologic  variations,  which  can  appear  in  the 
most  different  parts  of  the  organism,  are  to  be  ascribed 


Conditions  Necessary  for  Inheritance  287 

to  specific  alterations  of  a  single  form  of  energy,  so  that 
the  latter  appears,  as  it  were,  the  common  denominator 
for  these  variations  that  are  quite  unlike  in  nature  and 
whose  combination  or  separation  is  thus  permitted  as 
often  as  required. 

2.  The  determinative  influence  which  the  germ  sub- 
stance in   its   totality  exerts   upon  the   soma  cannot  be 
limited  to  the  first  moment  of  the  first  cleavage  of  the 
egg  but  must  persist  throughout  the  whole  of  ontogeny 
up  to  the  adult  condition,  so  that  the  germinal  substance 
never  as  it  were  loses  touch  with  the  soma,  but  rather 
remains   in  a  continual  state  of   reciprocal  action  and 
reaction  with  it. 

3.  The  influence  exerted  by  the  soma  in  this  way 
must  be  reversible,  that  is  the  germ  substance  must  be 
influenced  in  such  a  way  that  it  can  call  forth  again  at  the 
proper  moment,  at  the  numberless  different  points  of  the 
soma   of  the  new   organism,    all   the   same,   respective, 
special,  somatic  conditions  by  whose  complex  modes  of 
being  the  germ  substance  itself  was  already  influenced  in 
the  parent  organism  in  so  special  a  way. 

This  last  condition  which  alone  implies  in  itself  the 
whole  question  of  inheritance  falls  again  into  two  parts. 
First  the  germ  substance  must  be  influenced  always  in 
such  a  way  that  it  is  capable  of  giving  back  at  the  required 
moment  the  same  influence,  qualitatively  identical  but  in 
the  reverse  direction,  which  it  had  already  experienced 
as  the  single  resultant  of  all  the  elementary  somatic  in- 
fluences to  which  this  germinal  substance  was  simulta- 
neously subjected  in  the  preceding  organism.  Second: 
the  germ  substance  which  thus  gives  back  again  the 
influence,  by  which  it  was  influenced,  qualitatively 
identical  but  in  reverse  direction,  must  be  localized  at  a 


288  Theories  Treating  of  Inheritance 

single  definite  point  of  the  organism,  which  is  always  the 
same,  both  when  the  parent  soma  exerts  its  influence  upon 
the  germ  substance  which  it  contains,  and  also  when  the 
latter  exerts  upon  the  new  organism  its  own  determina- 
tive ontogenetic  influence. 

It  is  therefore  our  task  now  to  investigate  in  the 
following  chapter  whether  the  centroepigenetic  hypothesis 
already  set  forth  above  really  satisfies  all  these  conditions 
and  is  consequently  capable  of  really  affording  the  ade- 
quate explanation  for  the  inheritance  of  acquired 
characters,  which  we  seek. 


CHAPTER  SEVEN 

THE  CENTROEPIGENETIC  HYPOTHESIS  AND  THE  EXPLANA- 
TION  OF  INHERITANCE  AFFORDED  BY  IT. 

As  we  said  at  the  end  of  the  third  chapter,  when  the 
end  of  development  is  reached,  and  there  comes  with  it  a 
cessation  of  the  steady  activation  by  the  central  zone  of 
new  specific  potential  elements,  there  is  also  a  cessation  of 
the  perturbing  action  which  that  zone  had  up  till  then 
exercised  upon  the  dynamic  equilibrium  of  each  onto- 
genetic  stage;  so  that  the  organism  attains  at  that 
moment  the  final  equilibrium  of  the  adult  state.  But  we 
should  note  that  a  new  perturbing  influence  can  now 
come  into  play,  namely,  the  functional  stimulus  in  the 
widest  sense  with  all  its  innumerable  variations. 

In  the  same  manner,  we  said,  as  the  perturbing 
action  of  the  central  zone  had  formerly  upset  the  equili- 
brium which  was  but  just  formed,  and  so  provoked  the 
passage  of  the  organism  to  a  new  ontogenetic  state,  so 
now  each  lasting  change  of  the  functional  stimulus  by 
disturbing  the  dynamic  equilibrium  of  the  adult  state,  will 
induce  another  general  distribution  of  nervous  energy. 
Consequently  each  cell  of  the  entire  organism  or  of  cer- 
tain portions  of  the  organism  will  now  be  traversed  by  a 
nervous  flux  which  is  specifically  different  from  that  be- 
fore existing,  and  specifically  different  in  different  cells. 

In  each  nucleus  of  these  cells,  we  continued,  a  par- 

289 


290  Explanation  of  Inheritance 

ticular  specific  potential  element  will  consequently  be 
formed  and  deposited,  which  will  be  added  to  the  element 
or  elements  already  present.  All  these  elements,  new  as 
well  as  old,  deposited  in  the  somatic  nuclei,  will,  however, 
be  lost  with  the  death  of  the  individual;  and  those  alone 
will  escape  this  destruction  which  are  deposited  in  the 
germinal  substance  of  the  central  zone.  The  lasting 
variation  of  the  functional  stimulus  will  thus  have  had 
for  its  total  effect,  in  so  far  as  the  species  is  concerned, 
the  simple  addition  of  a  new  specific  potential  element  to 
the  germinal  substance. 

Arrived  at  this  point,  we  reserved  for  one  of  the 
following  chapters  the  examination  of  the  manner  in 
which  this  new  element  would  act  in  the  ontogeny  of  the 
next  following  organism.  It  is  then  with  this  examina- 
tion that  we  must  now  occupy  ourselves  in  the  present 
chapter. 

We  should  first  dwell  a  little  more  in  detail  upon  this 
hypothesis,  which  we  mentioned  only  in  passing  in  con- 
nection with  the  posthumous  action,  or  "Nachwirkung," 
of  the  nucleus  in  enucleated  fragments  of  unicellular 
forms.  We  mean  the  hypothesis  that  the  substance 
which  constitutes  each  specific  element,  and  which  is  cap- 
able of  giving  as  discharge  a  single  well-determined 
specific  nerve-current,  is  also  the  same  and  only  substance 
which  this  specific  nerve-current  can  in  its  turn  form  and 
deposit. 

This  should  not  appear  so  very  strange  to  us,  since 
the  inorganic  world  itself  presents  a  phenomenon  similar 
in  certain  respects.  The  substance  which  actually  con- 
stitutes the  charge  of  ordinary  electric  accumulators  is 
capable  of  giving  back  inversely,  during  its  discharge,  the 
same  kind  of  energy  which  it  had  previously  received, 


Accumulators  of  Specific  Nervous  Energy       291 

and  by  which  it  had  itself  been  deposited,  namely  the 
continuous  electric  current.  The  most  important  differ- 
ence consists  in  this,  that  an  electric  accumulator  is 
capable  of  restoring  always  only  one  and  the  same  kind 
of  energy,  but  not  solely  such  or  such  intensity  of  current. 
It  constitutes,  for  that  reason,  only  a  generic  potential 
element;  but  such  accumulators  would  attain  the  com- 
pleteness of  specific  potential  elements — receiving  and 
restoring  instruments  of  the  greatest  delicacy — if  one 
could  make  it  possible  that  each  one  of  them  should  re- 
ceive and  restore  only  a  single  definite  intensity  of  current. 
The  similarities  and  differences  which  nerve  currents 
present,  in  comparison  with  electric  currents,  quite  war- 
rant us  in  assuming  in  nerve  currents  some  of  the 
properties  of  electric  currents,  and  in  attributing  at  the 
same  time  to  the  first  other  properties  which  the  electric 
do  not  possess,  provided  these  qualities  are  not  incom- 
patible with  the  others. 

It  is  known  that,  if  we  designate  by  E  the  electro- 
motor force  of  an  accumulator  or  of  any  electro-chemical 
generator,  it  can  furnish  currents  of  any  intensity  i 
whatever,  according  to  the  resistance  R  of  the  circuit, 
according  to  the  equation  i=E/R.  Thus, — even  though 
the  terms  of  motor  force,  of  resistance,  of  intensity,  or 
more  generally  of  specificity,  transferred  from  electric  to 
nervous  currents  are  very  indefinite — we  may  very  well 
venture,  nevertheless,  as  a  preliminary  trial  hypothesis, 
to  attribute  to  nervous  currents  as  among  the  properties 
which  they  might  have  analogous  to  electric  currents 
precisely  those  contained  in  this  equation. 

As  it  involves  nothing  incompatible  with  the  prop- 
erties expressed  by  this  equation,  we  may  imagine  a 
nervous  accumulator,  constituted  by  a  given  substance 


292  Explanation  of  Inheritance 

capable  of  being  produced  and  deposited  solely  by  a 
current  of  a  definite  intensity  or  specificity,  and  at  the 
same  time  capable  of  producing,  by  its  decomposition, 
this  current  only,  of  the  same  intensity  or  specificity  i  is 
that  of  the  charge.  This  accumulator,  then,  will  discharge 
itself  and  produce  this  current  as  often  as  its  nervo-motive 
force,  which  we  may  still  call  E,  is  sufficiently  great  to 
overcome  the  respective  resistance,  according  to  the 
equation :  E=iR. 

Finally,  we  can  assume  that  the  magnitude  of  this 
nervo-motive  force,  is  proportional  to  the  quantity  or 
mass  of  the  substance  which  has  been  gradually  deposited 
and  accumulated,  as  if  the  successive  infinitesimal  deposits 
of  this  substance  were  innumerable  little  Ley  den  jars  ar- 
ranged in  serial  order.  Then  the  greater  the  mass  of 
the  specific  substance  of  this  nervous  accumulator  the 
greater  in  proportion  will  be  the  resistance  which  its  dis- 
charge will  be  able  to  overcome.  At  the  same  time,  this 
accumulator,  capable  of  surmounting  by  its  current  of  a 
fixed  intensity  i  a  given  resistance  R,  will  be  capable  also 
of  surmounting  every  other  resistance  less  great  than  R ; 
for  to  effect  that,  it  will  suffice  that  it  be  not  the  total 
quantity  of  material  at  disposal  that  enters  into  action, 
but  only  a  portion  more  or  less  large,  so  as  to  furnish  for 
each  resistance  R'<R,  the  nervo-motor  force  E'<E, 
given  by  the  formula : 

E'=iR' 

Suppose  now  that  the  discharge  of  this  accumulator 
on  account  of  the  ubication  or  the  mode  of  its  insertion, 
is  able  to  flow  only  upon  a  definite  point  of  a  given  plexus 
traversed  along  its  meshes  by  as  many  currents  of  the 
most  diverse  specificities  capable  of  combining  one  with 


Accumulators  of  Specific  Nervous  Energy       293 

another  and  of  decomposing  again,  and  in  dynamic 
equilibrium  among  themselves.  (It  may  be  remarked 
here  that  the  expression  "dynamic  equilibrium"  of  a  cir- 
culatory system  is  always  to  be  understood  in  the  sense 
of  inalterability  for  the  time  in  the  conditions  of  move- 
ment at  each  point  of  the  system.  Thus,  for  example, 
the  system  of  distribution  of  the  drinking  water  of  a  city, 
which  is  fed  from  a  given  constant  number  of  reservoirs, 
whose  head  of  water  is  maintained  always  at  the  same 
height,  and  in  which  a  given  constant  number  of  water 
taps  are  always  open,  will  settle  in  a  short  time  into  a 
dynamic  equilibrium  in  our  sense,  and  continue  in  it  so 
long  as  the  accession  of  a  new  reservoir,  for  example,  or 
the  opening  of  other  water  taps  does  not  cause  the  transi- 
tion to  a  new  dynamic  equilibrium.) 

As  soon  as  the  discharge  of  this  nervous  accumulator 
occurs,  which  can  produce  thus  only  a  single  definite 
specificity  of  current,  and  which  can  discharge  itself  upon 
only  a  single  fixed  point,  it  will  necessarily  effect  a  single 
very  definite  change  in  the  dynamic  equilibrium  of  this 
given  circulatory  system.  And  in  the  cases  in  which  this 
change  of  the  dynamic  equilibrium  requires  the  doing  of 
a  certain  amount  of  work,  this  required  expenditure  of 
work  or  energy  will  be  very  definite  for  each  discharge, 
and  can  be  provided  only  by  the  accumulator  itself.  Con- 
sequently, in  order  that  the  discharge  may  take  place,  this 
quantity  will  have  to  be  less  than,  or  at  most  equal  to, 
that  which  the  accumulator  can  actually  furnish. 

But  the  quantity  of  work  which  each  accumulator  is 
capable  of  furnishing  will  necessarily  be  proportional  to 
the  mass  of  the  substance  which  constitutes  it.  And 
since,  as  we  saw,  the  resistance  R  which  each  accumulator 
with  its  current  of  definite  specificity  is  able  to  surmount, 


294  Explanation  of  Inheritance 

is  likewise  proportional  to  the  mass  of  the  substance  of 
the  accumulator,  (because  it  is  proportional  to  its  nervo- 
motive  force,  which  also  is  in  its  turn  proportional  to  this 
mass,  according  to  the  preliminary  hypothesis),  then  the 
quantity  of  work  required  to  effect  the  change  under  con- 
sideration, must  be  regarded  as  equivalent  to  a  resistance 
R,  which  opposes  the  discharge. 

If  now  we  assume  that  in  nearly  all  cases,  which  come 
into  consideration  here,  the  quantity  of  work,  requisite 
for  effecting  a  given  change  in  the  dynamic  equilibrium 
of  the  whole  circulatory  system,  is  proportionately 
greater  the  more  considerable  (if  we  may  be  pardoned 
for  this  much  too  indefinite  expression)  in  quantity  and 
quality  this  change  is,  it  becomes  at  once  conceivable  why 
each  specific  potential  element  of  the  central  zone  can 
becomes  activated  only  when  the  embryo  has  reached 
the  ontogenetic  stage,  corresponding  to  the  particular 
phylogenetic  stage  at  which  this  element  was  acquired  by 
the  germinal  substance.  For  then  first  will  the  change 
which  the  dynamic  system  of  the  embryo  undergoes,  as 
a  result  of  the  activation  of  this  specific  potential  element, 
be  the  very  least  possible,  and  therefore  usually  also  the 
only  one  whose  resistance  can  be  surmounted  by  the  very 
weak  nervo-motor  force  of  this  specific  potential  element. 
The  following  general  rule  can  thus  be  established : 
The  smaller  the  mass  and  therefore  the  nervo-motor 
force  of  a  specific  accumulator,  so  much  the  more 
closely  is  its  discharge  dependent  upon  the  condition 
that  the  whole  dynamic  system,  above  all  and  very 
especially  in  the  immediate  neighborhood  of  the  ac- 
cumulator, find  itself  again  in  exactly  the  same  state  in 
which  it  was  when  the  accumulator  was  formed.  Con- 
versely, the  greater  the  mass  of  the  accumulator,  the 


Conditions  and  Effects  of  Discharge  295 

more  easily  are  the  conditions  to  be  obtained  which  are 
able  to  permit  its  discharge. 

Let  us  suppose  further  that  as  a  result  of  external  in- 
influences  there  are  induced  at  the  same  moment  at  a  few 
points  of  the  system  a  corresponding  number  of  new 
nerve  currents,  specifically  different  from  the  preceding, 
so  that  the  system  is  thereby  caused  to  pass  over  to  an- 
other dynamic  equilibrium.  It  is  clear  that  there  will 
then  be  deposited  in  each  point  of  the  system, — and  not 
merely  in  those  which  external  influences  have  directly 
modified, — a  new  specific  potential  element,  in  mass  more 
or  less  large  according  to  the  time  during  which  the  new 
state  of  dynamic  equilibrium  persists.  At  the  same  time, 
however,  all  these  same  points  of  the  system  will  preserve, 
in  a  potential  state — not  in  activation — ,all  the  specific  ele- 
ments which  were  desposited  during  the  preceding  state 
of  dymanic  equilibrium. 

If,  such  being  the  state  of  things,  it  now  happen  that 
even  any  single  point  whatever  of  the  system  is  brought 
back  again,  by  any  external  influence,  to  the  specificity 
which  it  had  already  possessed  in  the  preceding  stage, 
that  will  make  it  possible  for  the  respective  specific  ele- 
ments corresponding  to  that  stage  to  come  again  into 
activity,  at  first  in  the  point  nearest,  and  then  from  next 
to  next  until  in  the  most  distant ;  for  then  each  of  these 
elements  will  find  its  immediate  environs  in  approximately 
the  same  conditions  as  when  its  corresponding  specific 
current  was  in  activity,  by  which  it  has  been  deposited.  ,It 
will  suffice  then  that  even  a  single  point  of  a  system  re- 
turn, through  the  action  of  external  influences,  to  its 
preceding  state,  in  order  that  the  whole  system,  through 
the  discharge  of  the  different  specific  potential  elements 
corresponding  to  that  former  stage,  should  resume 


296  Explanation  of  Inheritance 

transitorily  the  whole  dynamic  condition  of  that  stage. 
We  have  here  then  a  phenomenon  of  succession  or  of 
association  of  nerve-currents  which,  as  is  easily  conceiv- 
able and  becomes  even  clearer  later,  may  serve  as  a  basis 
for  the  psychic  law  of  succession  or  association  of  ideas. 

In  resume,  what  we  have  designated  hitherto  by  the 
name  of  specific  potential  element,  and  what  we  may 
henceforth  designate  by  the  name  of  elementary  nervous 
accumulator,  is  then  nothing  else,  by  hypothesis,  than  the 
substance  of  a  very  small  mass,  deposited  in  the  nucleus 
by  every  specific  nervous  current  which  flows  through  it, 
— a  substance  which  adds  itself  to  the  others  already 
present  without  changing  them,  and  which  is  able  as  soon 
as  it  finds  itself  again  in  conditions  of  environment  like 
those  present  at  the  moment  when  it  was  deposited,  to 
restore  the  same  specific  current  by  which  it  was 
produced. 

This  definition  and  the  hypothesis  involved  answers  at 
once  the  question  as  to  the  mode  of  action  which  the  new 
specific  potential  element,  acquired  by  the  germinal  sub- 
stance of  the  central  zone  of  an  adult  organism  in 
consequence  of  a  new  functional  adaptation  in  this  or- 
ganism, will  follow  during  the  ontogeny  of  the  next 
following  organism.  For  from  all  we  have  thus  far  said, 
it  results  that  this  new  specific  potential  element  will  first 
be  able  to  become  active  when  the  embryo  shall  have  al- 
ready attained  the  same  state  in  which  the  parent 
organism  found  itself  immediately  before  it  acquired  this 
same  new  specific  potential  element  along  with  the  new 
character. 

Let  us  consider  now  what  happens  as  a  result  of  its 
activation:  In  the  parent  organism  there  was  present  at 
first  a  certain  circulatory  system  S,  corresponding  to  the 


Effects  of  Discharge  or  Activation  297 

adult  stage  preceding  the  acquisition  of  the  new  character. 
Then  on  account  of  an  external  influence  acting  at  a  given 
point  A  of  this  system,  the  specificity  of  the  respective 
current  was  changed  from  i  to  i' .  In  consequence  of  that 
the  whole  circulatory  system  S,  in  order  to  assume  a  new 
state  of  dynamic  equilibrium,  transformed  itself  into  a 
different  system  S',  in  such  a  way  that  at  another  given 
point  B,  that  of  the  central  zone,  the  specificity  of  the  re- 
spective current  underwent  a  very  definite  corresponding 
variation  from  intensity  U  to  i'i.  If  then  there  is  now 
present  in  the  embryo  of  the  young  organism  the  same 
circulatory  system  S  of  the  parent  organism,  and  if,  on 
account  of  the  activation  of  the  specific  potential  element 
in  question,  there  is  produced  at  the  same  point  B  of  this 
system,  the  same  variation  of  specificity  from  intensity 
ii  to  i'i,  it  is  evident — and  we  shall  see  later  that  a  few 
facts  from  the  inorganic  world  prove  experimentally  the 
general  principle  upon  which  our  assertion  rests — that 
there  must  follow  the  same  change  as  before  of  the 
dynamic  equilibrium  of  the  general  system  from  S  to  S', 
and  that,  consequently,  there  will  now  be  produced  at 
the  point  A  the  same  specific  modification  as  before  from 
i  to  i'.  In  this  way  the  inheritance  of  acquired  characters 
finds  a  most  complete  explanation. 

Let  us  note  parenthetically,  that  nuclear  somatization 
conceded,  we  must  regard  each  of  the  substances  forming 
the  different  specific  potential  elements  of  any  nucleus  as 
capable  of  gradually  replacing  the  others  by  continual  in- 
crease of  its  mass,  when  the  respective  specific  current,  on 
account  of  the  incessant  repetition  always  of  only  one  and 
the  same  stimulus,  passes  very  frequently  through  the 
nucleus.  A  nucleus  thus  somatized, — that  is  to  say,  one 
composed  wholly  of  a  single  specific  substance, — would 


298  Explanation  of  Inheritance 

acquire  in  this  way,  on  account  of  the  considerable  mass 
of  this  substance,  a  potential  energy  capable  of  over- 
coming a  considerable  resistance  to  its  discharge,  and 
would  then  be  able  to  respond  always  in  that  single  way 
only  which  corresponds  to  the  single  specific  nervous  cur- 
rent which  it  is  able  to  activate  and  which  constitutes  its 
irritability,  even  if  it  be  provoked  to  discharge  by  external 
influences  or  accidental  stimuli  which  are  quite  different 
from  those  to  which  it  is  ordinarily  exposed. 

"A  muscle  cell,"  says  Oscar  Hertwig,  "replies  to  every 
kind  of  stimulus  by  contraction,  a  gland  cell  by  secretion; 
an  optic  nerve  can  perceive  only  light,  no  matter  whether 
it  be  stimulated  by  light  waves,  by  electricity  or  by  press- 
ure. Similarly  plant  cells  also  are  endowed  with  their 
own  specific  energies :  the  reaction  to  stimulation  re- 
ceives everywhere  its  specific  stamp  from  the  special  struc- 
ture of  the  irritable  substance,  or  in  other  words, 
irritability  is  a  fundamental  property  of  living  protoplasm, 
but  under  the  action  of  the  environment  manifests  itself 
in  specific  reactions  according  to  the  specific  structure  of 
that  protoplasm."  216 

And  Claude  Bernard  defined  irritability  as :  "the 
property  of  living  elements  of  reacting  each  according  to 
its  nature  to  an  external  provocation  or  stimulus."217 

"One  conceives  of  the  irritable  substance,"  continues 
Hertwig,  "as  a  system  of  material  particles  in  unstable 
equilibrium,  provided  with  forces  at  high  tension.  In 
such  a  system,  a  very  small  shock  of  a  single  particle  is 
sufficient  to  put  all  the  other  particles  in  motion,  each 
transmitting  its  own  motion  to  its  neighbor.  That  ac- 

21flOscar  Hertwig :   Die  Zelle  und  die  Gewebe.    I,  P.  76. 
217Claude  Bernard:    Legons  sur  les  phenomenes  de  la  vie  com- 
muns  aux  animaux  et  aux  vegetaux.     P.  248,  281. 


The  Only  New  Thing  in  the  Hypothesis  299 

counts  for  the  fact  that  a  small  stimulus  as  cause  may 
often  result  in  an  extraordinarily  great  reaction,  just  as 
a  grain  of  gunpowder  kindled  by  a  small  spark  may 
provoke  the  explosion  of  a  great  mass."  218 

We  have  opened  this  parenthesis  on  nuclear  somatiza- 
tion  and  cited  these  passages  from  the  two  investigators 
in  order  to  set  in  clear  relief  the  fact  that  in  the  definition 
given  above  of  the  specific  potential  elements,  both  the 
conception  of  accumulators  of  nervous  energy  in  tension, 
and  that  of  accumulators  of  a  specific  nervous  energy  con- 
stituting their  special  irritability,  are  ordinary  conceptions 
very  generally  employed  which  are  expressed  here  in 
words  at  most  only  a  little  different  from  the  ordinary. 
The  only  new  thing  which  the  above  definition  includes 
is  the  hypothesis  that  the  substance  which  is  thus  capable 
of  giving  as  a  discharge  a  given  nervous  current  was  pro- 
duced and  deposited  only  by  a  nervous  current  of  the 
same  specificity,  but  in  the  inverse  direction,  and  could 
have  been  produced  and  deposited  only  by  such  a  current. 
But  in  this  hypothesis,  quite  simple  as  it  is,  lies  every- 
thing; for  it  is  just  it  which  alone  can  explain  completely 
the  fundamental  law  of  the  reversibility  of  the  relation 
between  action  and  reaction,  between  stimulus  and  im- 
pression, which  governs  all  organic  life.  The  inheritance 
of  acquired  characters,  the  psycho-mnemonic  phenomenon 
proper,  the  process  of  specialization  and  somatization  of 
the  cells  in  consequence  of  which  they  react  in  their 
habitual  manner  to  accidental  stimuli  unusual  to  them, 
even  the  vital  phenomenon  itself  in  all  its  generality,  all 
of  these,  as  we  have  seen  and  shall  see,  are  only  so  many 

S180scar  Hertwig :   Die  Zelle  und  die  Gewebe    I,  P.  77. 


300  Explanation  of  Inheritance 

special  cases  of  this  reversibility,  and  all  find  their  im- 
mediate explanation  in  this  very  simple  hypothesis. 

In  resume :  By  this  hypothesis  of  a  nervous  accumu- 
lator formed  and  deposited  by  the  same  specific  current 
which  it  can  afterward  restore,  the  first  of  the  two  sub- 
conditions,  included  in  the  third  condition,  necessary  and 
sufficient  to  account  for  the  inheritance  of  acquired  char- 
acters, are  fulfilled.  On  the  other  side  the  localization  of 
the  germinal  substance  in  the  central  zone,  which  con- 
stitutes the  point  of  departure  and  the  foundation  for  the 
hypothesis  of  centroepigenesis,  has  already  satisfied  com- 
pletely the  second  of  these  sub-conditions.  As  to  the  two 
other  conditions,  the  first  has  already  been  satisfied  by 
considering  the  nervous  current  with  its  numerous  differ- 
ent specificities  as  the  common  denominator  or  as  the 
basis  of  vital  phenomena  of  the  most  diverse  kinds  which 
are  in  activity  at  each  instant  in  the  most  varied  points  of 
the  soma;  the  second  was  satisfied  by  assuming  a  con- 
tinuous action  on  the  part  of  the  germinal  substance 
throughout  the  whole  of  ontogeny,  by  means  of  the 
steady  activation  of  new  specific  potential  elements  pour- 
ing their  discharges  into  the  general  circulatory  system. 
It  follows  from  this  that  centroepigenesis  is  able  singly 
and  alone  to  explain  the  inheritance  of  acquired  char- 
acters, because  it  fulfills  these  conditions  which  we  rightly 
regarded  not  only  as  necessary,  but  also  as  sufficient. 

For  greater  clearness,  nevertheless,  it  will  be  worth 
while  to  institute,  as  we  have  indicated  above,  a  compar- 
ison between  this  ontogenetic  development,  as  it  would  be 
constituted  according  to  the  hypothesis  of  centro- 
epigenesis, and  a  very  characteristic  phenomenon,  in  some 
respects  analogous,  which  is  presented  by  the  inorganic 
world.  The  reproduction  of  a  sentence  by  a  phonograph 


Comparison  with  Phonograph  and  Telephone      301 

is,  in  fact,  if  the  expression  be  allowed,  a  true  centro- 
epigenesis.  The  needle  placed  at  the  center  of  the 
membrane  repasses  through  all  the  stages  through  which 
it  had  passed  when  the  sentence  was  spoken;  and  each  of 
these  stages  was  only  the  total  effect  of  the  repercussion 
upon  this  point  of  all  the  extremely  complex  vibrations 
called  forth  in  the  membrane  by  external  influences,  in 
this  case  the  vibrations  in  the  air.  Since  the  needle, — one 
single  point  of  the  dynamic  system, — repeats  thus  the  same 
identical  series  of  specific  movements  which  were  before 
produced  at  this  point  by  the  concurrence  and  union  of  all 
the  complex  movements  of  the  system,  these  successive 
specific  movements  of  this  one  point  are  thereby  again 
decomposed  into  all  the  same  successive  complex  modes 
of  the  entire  dynamic  system,  in  this  case  constituted  by 
the  extremely  complex  vibrations  of  the  membrane. 

Let  us  suppose,  moreover,  that  it  were  possible  to 
interpose  in  an  ordinary  telephone  wire  transmitting  a 
series  of  variations  of  the  electric  current  a  complex  ac- 
cumulator capable  of  receiving  the  current  and  of  return- 
ing it  after  a  certain  time  just  as  it  was  in  its  successive 
variations.  Then  the  whole  series  of  complex  dynamic 
systems,  which  were  formed  by  the  successive  complex 
vibrations  of  the  membrane  receiving  the  spoken  words 
could  be  reproduced,  just  as  at  the  receiving  station,  after 
any  interval  whatever,  exactly  as  with  the  phonograph. 
Well,  the  role  which  centroepigenesis  attributes  to  the 
germinal  substance  is  fundamentally  nothing  else  than 
that  it  forms  a  similar  complex  accumulator. 

Finally  it  may  appropriately  be  noted  here,  that  this 
comparison  with  the  phonograph  permits  us  to  make  still 
more  definite  and  clear  all  that  we  stated  at  the  end  of 
the  fourth  chapter,  namely  that  the  centroepigenetic 


302  Explanation  of  Inheritance 

hypothesis  is  able  to  explain  participate  inheritance  com- 
pletely, without  requiring  the  help  of  any  preformistic 
germs  whatever.  Concretely:  let  us  imagine  two  exactly 
similar  phonographs,  and  let  us  have  the  same  singer 
render  the  same  melody  in  exactly  the  same  way  first 
before  one  then  before  the  other.  Only  let  us  suppose 
that  one  hears  at  a  certain  moment  during  the  second 
song,  for  example,  one  of  the  audience  cough,  or  a  door 
slam,  or  clapping  of  applause.  Obviously  both  phono- 
graphs now  will  reproduce  the  same  melody  in  the  same 
way,  with  the  single  difference  of  the  accessory  noise, 
which  will  not  destroy  in  the  slightest  the  otherwise  com- 
plete conformity  of  the  two  phonographic  reproductions. 
Thus  we  have  here  an  actual  and  characteristic  case  of 
particulate  inheritance  for  the  production  of  which  it  is 
mechanically  sufficient  that  the  series  of  successive  specific 
vibrations  of  the  middle  point  of  the  membrane  differs 
from  the  corresponding  series  of  vibrations  in  the  other 
phonograph  only  through  a  single  vibration  or  through 
a  very  inconsiderable  group  of  these  specific  vibrations. 

From  the  explanation  which  centroepigenesis  gives  of 
the  inheritance  of  acquired  characters  there  follows  also 
at  once  a  very  important  consequence.  If  we  mean  by 
functional  stimulus  not  so  much  the  external  influence  as 
rather  the  immediate  modification  induced  by  it  in  the 
vital  process,  then  the  functional  stimulus  according  to 
the  centroepigenetic  hypothesis  is  of  quite  the  same 
nature  as  the  ontogenetic  stimulus.  And  this  appears  to 
be  indicated  also  by  the  best  demonstrated  facts. 

We  regard  it  as  absolutely  necessary  to  understand 
first  clearly  this  distinction  between  external  physical 
actions  and  functional  stimulus.  For  the  former  do  not 
themselves  constitute  the  true  and  proper  functional 


Functional  and  Ontogenetic  Stimuli  303 


stimuli,  but  they  do  determine  them.  External  influences 
and  functional  stimuli  are  two  special  forms  of  energy, 
the  first  of  which  can  transform  itself  into  the  second, 
but  they  are  fundamentally  different  from  each  other. 
The  one  is  inorganic,  the  other  biologic  and  vital  in 
nature.  And  the  designation  "functional  stimulus" 
properly  applies  to  the  external  action,  in  so  far  as,  and 
at  the  moment  when,  it  transforms  itself  into  vital 
energy.  The  possibility  of  a  substantial  identity  between 
the  functional  stimulus  and  the  ontogenetic  stimulus  can 
obviously  exist  only  in  case  the  former  is  understood  in 
this  way. 

That  being  disposed  of,  it  becomes  worth  while  to 
recollect  that  Roux  distinguishes  embryonic  life  and  adult 
life  as  two  things  of  totally  different  nature:  "In  the 
life  of  all  parts  (of  the  organism)  two  periods  must  be 
distinguished :  an  embryonic  period  in  the  widest  sense 
in  which  the  parts  develop,  differentiate,  and  grow  of 
themselves,  and  an  adult  period  in  which  growth,  and  in 
many  parts  indeed,  the  complete  replacement  of  material 
used  up,  goes  on  only  with  the  co-operation  of  stimuli. 
These  stimuli  might  thus  give  origin  to  something  new 
which,  if  it  were  produced  in  this  manner  throughout 
several  generations,  would  become  hereditary,  that  is,  be 
formed  without  these  stimuli  in  the  descendant,  and  be- 
come thus  in  our  sense  embryonal."  219 

These  two  periods  characterized  respectively  by 
embryonic  differentiations  and  by  functional  changes  are 
regarded  by  Roux,  as  we  have  said,  as  essentially  differ- 
ent :  "Since  the  changes  going  on  in  adult  men,  are  pro- 
duced only  by  means  of  external  transforming  influences, 

219Roux:    Der  Kampf  der  Teile  im  Organismus.    P.  180—181. 


304  Explanation  of  Inheritance 

whereas  embryonal  differentiations,  on  the  other  hand, 
take  place  without  or  almost  without  such  differentiating 
stimuli,  there  is  reason  to  believe  that  these  results  are 
produced  in  another  way  which,  while  undoubtedly  con- 
trolled by  natural  laws,  is  nevertheless  for  the  time 
incomprehensible  by  us.  Consequently  the  essence  of 
embryonic  differentiation  and  its  immediate  physico- 
chemical  causes  are  for  the  moment  quite  inaccessible  to 


us."  22° 


Centroepigenesis,  on  the  contrary,  teaches  us,  as  we 
have  seen,  that  embryonic  and  functional  differentiation 
are  essentially  the  same.  And  in  support  of  this  view  we 
may  recall  among  others  the  following  principal  orders 
of  facts: 

"All  the  organs  which  fulfill  their  specific  function 
already  in  the  embryo  have  there  a  life  dependent  upon 
stimulus  (Reizleben)  in  proportion  to  this  function."221 
This  indicates  that  an  organism  in  process  of  develop- 
ment may  be  at  one  and  the  same  moment  in  the 
embryonic  period  in  respect  to  some  of  its  parts  and  in 
the  functional  period  in  respect  to  other  parts,  without 
ceasing  for  that  reason  to  behave  in  all  its  manifestations 
as  a  whole  of  a  thoroughly  individual  nature. 

A  number  of  characters  begin  to  develop  embryon- 
ically  which  later  require  the  help  of  the  functional 
stimulus  to  complete  their  development :  "In  embryonic 
development  some  parts  are  ontogenetically  formed  and 
developed  to  a  certain  grade  of  functional  capacity,  which 
have  been  formed  phylogenetically  entirely  by  functional 
adaptation.  Functional  stimuli  seem  to  be  necessary  only 
for  that  remainder  of  development  which  belongs  from  its 

220Roux :    Ibid.    P.  166. 

221Roux:    Der  Kampf  der  Teile  im  Organismus.    P.  182. 


Functional  and  Ontogenetic  Stimuli  Alike       305 

essence  to  functional  life  proper."  222  This  would  speak 
for  the  gradual  accomplishment  of  the  transition  from 
the  embryonal  to  the  functional  period  without  any  sud- 
den and  precipitate  change,  and  so  speaks  also  for  a 
gradual,  hardly  noticeable  replacement  of  the  ontogenetic 
stimulus  by  the  functional  so  that  one  must  suppose  the 
two  stimuli  to  be  active  simultaneously  and  in 
combination. 

So  Hyrtle,  having  cut  across  the  motor  nerves  of  the 
muscles  of  one  side  of  the  face  of  a  new  born  rabbit, 
stated  that  a  year  after  there  was  not  only  atrophy  of 
the  muscles  but  the  bones  of  that  side  of  the  head  had 
undergone  a  surprising  arrest  of  growth.  He  attributed 
this  arrest  to  the  fact  that  "after  muscular  paralysis  there 
was  lacking  the  traction  and  compression,  which  provoke 
living  parts  of  the  bone  to  activity  and  cause  the  normal 
growth  of  the  bone."  223 

Alesandrini  and  E.  H.  Weber  similarly  found  in 
monsters  "that  in  the  absence  of  the  anlage  of  the  spinal 
cord  there  were  lacking  in  the  corresponding  nerve  ter- 
ritory both  the  nerves  and  the  muscles  and  that  the  bones 
and  joints  belonging  to  these  were  abnormally  formed, 
the  latter  being  in  part  rigid."  224 

It  may  be  remarked  here  that  as  some  of  these  parts 
had  attained  a  certain  development  even  without  the 
functional  stimulus,  and  during  the  very  period  in  which 
normally  they  would  have  had  the  co-operation  of  the 
functional  stimulus,  it  is  therefore  clear  that  if  there  had 


822Roux:  Zur  Orientierung  iiber  einige  Probleme  der  embry- 
onalen  Entwicklung.  Zeitschrift  fur  Biologic.  Bd.  XXI;  Miinchen, 
July  1885,  P.  503.  Gesammelte  Abhandlungen,  II,  P.  231—232. 

228Oscar  Hertwig :   Die  Zelle  und  die  Gewebe.    II,  P.  175. 

22*Roux :    Der  Kampf  der  Teile  im  Organismus.    P.  51. 


306  Explanation  of  Inheritance 

not  been  this  pathological  absence  of  this  latter,  the 
ontogenetic  stimulus  and  the  functional  would  have  co- 
operated at  the  same  time  in  the  same  formation.  There- 
fore one  cannot,  as  we  have  said,  be  oblivious  of  the 
indication  that  this  harmonious  and  parallel  co-operation 
of  the  two  stimuli,  in  combination  with  the  fact  that  in 
no  embryonic  structure  whatever  is  there  to  be  demon- 
strated any  substantial  difference  in  the  manner  of  forma- 
tion and  development  between  the  purely  hereditary 
portion  due  to  the  ontogenetic  stimulus  alone,  and  the 
portion  due  to  the  functional  stimulus,  is  strongly  in 
favor  of  the  essentially  identical  nature  of  these  two 
stimuli. 

Finally  a  number  of  organs  which  would  attain  their 
complete  development  through  the  ontogenetic  stimulus 
alone,  have  their  development  hastened  by  the  accidental 
intervention  before  the  proper  time  of  the  requisite 
functional  stimulus.  Thus,  for  example,  in  prematurely 
born  children  the  visual  sense  develops  earlier;  that  is  to 
say  its  development  is  accomplished  in  a  total  number  of 
days,  counting 'from  the  first  instant  of  development,  that 
is  smaller  than  the  ordinary  number  such  as  would  be 
given  by  the  time  of  ordinary  gestation  augmented  by 
the  number  of  days  necessary  for  the  infant  born  at  term 
to  acquire  the  same  degree  of  development  of  sight.225 
And  this  demonstrates  again,  that  the  functional  stimulus 
can  replace  the  ontogenetic  stimulus,  or  better,  that  it  can 
co-operate  with  it  and  add  itself  to  it,  thus  strengthening 
its  effect;  a  thing  which  would  be  difficult  to  conceive  of 
were  the  two  stimuli  of  different  nature. 

To  these  facts  of  the  most  general  character,  we  can 

22BRoux :     Der  Kampf  der  Teile  im  Organismus.     P.  182. 


Functional  and   Onto  genetic  Stimuli  Alike       307 

add  further  the  following  more  special  ones  which  are 
quite  similar  in  their  nature  to  the  preceding. 

The  tails  of  larval  amphibians,  cut  off  obliquely  in 
respect  to  their  axes,  become  regenerated  in  such  a  way 
that  the  axis  of  the  regenerated  fragment  is  always  per- 
pendicular to  the  plane  of  section  and  forms  consequently 
a  certain  angle  with  the  axis  of  the  stump.  Nevertheless, 
all  these  tails,  because  of  regulative  forces  within  the 
organism,  tend  gradually  to  straighten  themselves.  Now 
Barfurth  has  demonstrated  that  in  frog  larvae  which  are 
prevented  almost  entirely  from  swimming  by  putting 
them  in  shallow  water  divided  into  a  number  of  small 
compartments  by  water  plants,  this  straightening  goes  on 
in  a  much  less  complete  manner  and  much  more  slowly 
than  in  those  which  are  placed  in  deep  water  and  which 
are  thus  able  to  swim  freely.  That  is  a  proof  that  func- 
tional adaptation  of  the  tail  to  swimming  co-operates  with 
the  entire  action  of  the  internal  regulative  capacity,  or  in 
a  wider  sense  with  the  ontogenetic  stimuli,  and  adds  it- 
self to  them,  intensifying  and  accelerating  their  action.226 

An  example  of  the  ontogenetic  stimulus  having  not 
yet  replaced  the  functional,  or  better,  being  not  yet 
endowed  with  a  quantity  of  potential  energy  sufficient  to 
overcome  by  itself  the  resistance  which  opposes  its  acti- 
vation, and  which  has  therefore  need  of  this  functional 
stimulus  in  order  to  commence  to  act,  is  furnished  us 
by  the  axolotls.  These  tailed  batrachians  can  retain 
their  external  gills  indefinitely  and  live  out.  their  lives 
and  reproduce  their  kind  with  external  gills,  or  be  trans- 
formed into  amblystomae,  according  as  they  are  or  are 

22flBarfurth:  Versuche  zur  funktionellen  Anpassung.  Arch.  f. 
mikrosk.  Anatomic,  Bd.  XXXVII ;  Drittes  Heft.  Bonn,  Cohen  1891 ; 
especially  P.  403 — 405. 


308  Explanation  of  Inheritance 

not  prevented  from  passing  at  the  proper  moment  of 
their  development  to  terrestrial  life.  "One  could  say 
that  this  depends  upon  the  amblystomal  form  being  not 
yet  sufficiently  fixed  in  the  heredity  of  the  species,  since 
the  epigenesis  resulting  from  this  heredity  does  not  yet 
necessarily  cause  the  appearance  of  the  amblystomal  form 
so  long  as  the  conditions  to  which  this  form  is  adapted 
are  not  realized."  227 

Finally  the  experiments  of  Cunningham  on  the  colors 
of  flat  fishes  already  quoted  above,  are  well  known.  He 
has  shown  that  during  their  first  metamorphoses,  while 
the  pigment  is  still  present  on  both  sides,  the  action  of 
light  artificially  reflected  upon  the  side  of  the  fish  which 
is  turned  toward  the  bottom  does  not  prevent  the  pigment 
from  disappearing  even  then  from  that  side,  so  that  in 
this  case  the  color  passes  rapidly  through  a  retrograde 
development.  But  a  prolonged  exposure  to  light  pro- 
vokes the  reappearance  of  the  pigment  on  the  lower  side, 
and  the  pigment  spots  are  in  every  respect  like  those 
which  are  normally  present  on  the  upper  side  of  the 
fish/228 

In  this  experiment  then  one  has  a  clear  and  direct 
instance  of  a  functional  stimulus  reinforcing  the  onto- 
genetic  stimulus.  We  say  "reinforcing"  because  the  fact 
that  the  spots  now  appearing  on  the  lower  side  are  like 
those  above,  demonstrates  that  they  are  not  produced 
de  novo  by  the  functional  stimulus,  but  even  now  depend 
upon  the  o»togenetic  stimulus,  which,  with  the  help  of 


23TLe  Dantec:   Traite  de  Biologic.    P.  403-404. 

228Osborn:  The  hereditary  Mechanism  and  the  Search  for  the 
unknown  Factors  of  Evolution.  Biol.  Lect.  at  the  Mar.  Biol.  Lab.  of 
Wood's  Holl,  Summer  Session  1894.  Boston,  U.  S.  A.,  Gin-n,  1896. 
P.  91. 


Conclusions  309 

the  functional  stimulus  acquires  anew  the  power  which 
it  once  had  possessed  in  the  ancestors  of  the  existing 
species : — another  proof  that  the  functional  and  onto- 
genetic stimuli  can  act  at  the  same  time,  that  their 
actions  can  be  added  together,  and  that  they  must  con- 
sequently be  of  the  same  nature. 

We  can  then  draw  the  following  conclusions : 

1.  The  essential  similarity  of  the  two  stimuli,  onto- 
genetic  and   functional,   the  reality   of  which  the   facts 
which  we  have  just  cited  and   a   thousand  others  like 
them  permit  us  to  deduce,  combined  with  the  fact  that 
external    influences,    upon    which    alone    the    functional 
stimulus    depends,    are    generally    lacking    during    the 
embryonal  period,  is  sufficient  even  by  itself  to  justify 
us  in  concluding  that  ontogenetic  stimuli  are  nothing  else 
than  the  reactivation  and  restitution  of  the  functional. 
It  constitutes  thus  at  the  same  time  a  new  argument  in 
favor  of  the  inheritance  of  acquired  characters. 

2.  This  conception  of  development  based  upon  the 
essential  identity  of  the  functional  stimulus  and  the  onto- 
genetic stimulus,  and  up  till  now  at  least  only  this  con- 
ception, makes  it  possible  to  explain  the  ontogenetic  facts 
without  presupposing  in  any  of  the  stages  of  development 
any  phenomenon   which   is   not  a  normal   physiological 
phenomenon,  of  the  very  same  nature  as  those  mani- 
fested by  the  organism  in  the  adult  state.     And  it  thus 
indicates  that  the  whole  of  life,  at  every  moment  of  it, 
preserves  an  absolute  unity  in  its  nature. 

3.  Ontogeny    finally    appears    to    us    in    this    way 
simply    as   a    continual    functional    adaptation,    by    the 
embryo,  to  the  successive  active  modes  of  being  of  the 
central  zone  of  development. 

Having  thus  set  forth  and  explained  the  way  in  which 


310  Explanation  of  Inheritance 

centrocpigenesis  is  able  to  account  for  the  inheritance  of 
acquired  characters  in  general,  the  particular  case  of  this 
inheritance,  constituted  by  sexual  dimorphism  and  by 
polymorphism  in  general,  which  up  till  now  we  have 
been  compelled  to  leave  aside,  becomes  explained  at  once. 

The  question  of  primary  and  secondary  sexual  char- 
acters, writes  Delage,  is  connected  with  one  of  the  most 
important  questions  of  general  biology :  "When  one 
part  develops  in  a  certain  way  another  part  develops 
correlatively  in  a  certain  way,  and  if  the  first  had  devel- 
oped in  another  way,  the  development  of  the  second 
would  also  have  been  different;  and  this  although  no 
direct  connection  exists  between  these  two  parts.  The 
question  presents  itself  also  in  the  following  way:  In 
what  way  and  under  what  form  can  this  reciprocal 
influence  of  the  organs  acting  at  a  distance  be  effected 
without  any  similarity  between  cause  and  effect?"229 

The  explanation  which  the  centroepigenetic  hypothesis 
can  afford  for  sexual  dimorphism  is  the  following :  It  is 
due  to  the  fact  that  in  the  whole  series  of  germinal  specific 
potential  elements  there  are  found  interpolated  two  dis- 
tinct groups  of  these  elements,  such  that  the  activation 
by  the  central  zone  of  one  of  these  groups  would  pre- 
clude the  activation  of  the  other  and  vice  versa.  Then  as 
soon  as  the  two  sexes  have  commenced  to  differ  somat- 
ically  even  a  very  little  from  each  other,  every  later 
sexual  character,  whether  principal  or  secondary,  acquired 
by  functional  adaptation  by  the  male  or  female,  or  better 
the  entire  conformation  of  the  whole  organism  resulting 
therefrom,  would  become  represented  in  the  central  zone 
of  that  organism  by  a  corresponding  small  group  of 

229Delage:   L'heredite  etc.    P.  184—18$. 


Sexual  Dimorphism  and  Polymorphism  311 

specific  potential  elements.  And  these  could  become 
activated  in  the  next  following  organism  only  when  the 
general  distribution  of  its  nervous  energy  should  find 
itself  in  the  same  conditions  as  at  the  time  when  this 
new  sexual  character  was  acquired :  a  thing  which 
requires  above  all  that  the  organism  be  of  the  respective 
sex. 

In  harmony  with  this  the  ordinary  facts  of  embryonic 
development  teach  us  that  as  soon  as  the  sexual  organs 
of  one  of  the  sexes  become  indicated,  the  accessory 
organs  just  forming  of  the  other  sex  cease  to  develop 
and  remain  rudimentary,  while  the  organs  proper  to 
the  sex  which  is  already  declared,  both  the  essential  and 
the  secondary,  develop  completely.  There  is  thus  an 
arrest  of  growth  in  some  organs  from  the  fact  of  the 
development  of  the  others,  which  makes  one  suspect  that 
the  conditions  of  environment  created  by  this  develop- 
ment of  some  organs  hinder  the  further  activation  of 
energies  which  cause  the  production  of  organs  of  the 
other  sex. 

Thus  there  always  remains  latent  the  possibility,  that 
the  characters  of  the  other  sex  may  also  appear  in  an 
individual  already  developed  in  the  opposite  way,  espe- 
cially in  advanced  age,  when  with  the  cessation  of  their 
respective  functions  all  the  sexual  organs  and  characters 
lose  their  vitality;  a  thing  which  often  occurs  in  many 
species  and  in  man  himself,  and  which  occurred  partic- 
ularly in  that  famous  old  hen  which  Darwin  has  reported, 
which  after  having  ceased  to  lay  eggs  took  on  not  only 
the  voice,  but  the  plumage,  the  spurs,  and  the  fighting 
temperament  of  the  cock. 

One  can  say  the  same  of  polymorphism.  In  fact  this 
also  can  very  well  be  regarded  as  dependent  on  an  inter- 


312  Explanation  of  Inheritance 

polation,  quite  analogous  to  that  of  which  we  have 
spoken  above,  of  three  or  more  groups  of  specific  poten- 
tial elements  in  the  whole  series  of  germinal  elements, 
with  the  result  that  the  activation  of  one  of  these  groups 
prevents  that  of  all  the  others.  Thus  each  form  of  the 
polymorphous  kind  would  have  its  own  characters  which 
arise  entirely  by  the  inheritance  of  characters  acquired 
through  functional  adaptation. 

It  is  nevertheless  to  be  remarked  that  a  few  forms 
of  certain  polymorphous  species  are  possibly  to  be 
ascribed  also  to  the  circumstance  that  a  few  groups 
among  all  the  specific  potential  germinal  elements  of  the 
entire  series  are  hindered  in  their  activation,  not  so  much 
by  properly  ontogenetic  conditions  which  depend  upon 
the  development  of  other  characters,  as  rather  by  quite 
general  conditions  of  temperature,  nutrition,  etc.,  so  that 
thus  the  form  in  which  .hese  groups  are  not  activated, 
differs  from  the  principal  form  only  through  the  absence 
of  some  single  character.  This  might  be  the  case,  for 
example,  in  the  working  bees  and  generally  in  the  neuters 
of  many  insects,  the  explanation  of  which  would  thus 
be  quite  similar  to  that  which  Spencer  gives  in  his  polemic 
with  Weismann.  But  evidently  these  forms  with  incom- 
plete development  represent  essentially  only  a  special  case 
of  the  preceding  supposition. 

We  can  thus  say  also  that  the  fundamental  principle 
to  which  centroepigenesis  has  recourse  in  order  to  explain 
sexual  dimorphism  and  polymorphism  in  general,  that 
is,  to  explain  how  it  comes  about  that  the  development 
of  certain  characters  prevents  that  of  certain  others 
which  remain  latent,  is  still  the  same  principle  which 
has  already  served  to  explain  the  fact  that  ontogenetic 


Instincts  313 

characters  present  themselves  exactly  in  the  order  of 
their  phylogenetic  acquisition. 

If  the  capacity  which  centroepigenesis  possesses  of 
explaining  the  Lamarckian  principle  extends  so  far  as  to 
account,  without  needing  any  subordinate  hypothesis,  for 
the  inheritance  of  those  characters  also  which  either  sex 
has  acquired  separately  and  at  different  times  and  each 
on  its  own  account,  it  shows  itself  still  more  especially 
and  completely  adapted  to  explaining  the  inheritance  of 
those  characters  common  to  both  sexes  as  well  as  those 
belonging  only  to  one  sex  which,  in  consequence  of  their 
excessive  complexity  and  of  the  circumstance  that  they 
are  located  not  simply  in  definite  parts  of  the  organism 
but  rather  in  numberless  places  at  the  same  time,  have 
so  far  always  constituted  the  greatest  difficulty  for  every 
theory  which  has  attempted  to  explain  the  inheritance 
of  them.  We  refer  to  the  instincts. 

It  is  evident  in  fact  that  we  can  regard  every  instinct 
as  due  to  a  special  relative  mode  of  being  of  the  different 
psychic  centers  and  of  the  nervous  network  connecting 
them.  For  it  depends  upon  this  relative  mode  of  being 
that  to  certain  definite  sensations  which  arrive  at  certain 
perceptive  centers  there  correspond  necessarily  certain 
reflex  movements  induced  by  the  motor  centers  which 
are  in  definite  communication  with  these  perceptive 
centers.  Now,  however,  every  deposition  of  new  psychic 
centers,  perceptive  or  motor,  mnemonic  or  volitional, 
and  every  new  connection  of  these  by  means  of  nervous 
communications  more  or  less  direct  or  indirect,  more 
or  less  conductive  or  resistant,  would  be,  according  to 
the  centroepigenetic  hypothesis,  only  the  effect  of  as 
many  special  modes  of  being  of  nervous  circulation  in 
the  limited  territory  of  the  nervous  system  alone.  It 


314  Explanation  of  Inheritance 

is  therefore  easy  to  imagine,  above  all  if  we  recollect 
that  the  central  zone  would  be  just  one  part, — the  least 
differentiated  part  of  this  system,  that  for  each  one  of 
these  complex  modes  of  being  of  the  nervous  configura- 
tion constituting  a  given  instinct  there  must  correspond 
in  the  central  zone  itself  its  respective  specific  potential 
element,  and  this  latter  becoming  active  later  in  the  next 
following  ontogeny  as  soon  as  the  general  nervous  con- 
figuration again  becomes  like  that  which  was  present  at 
the  moment  immediately  preceding  that  in  which  this 
element  was  formed  in  the  parent,  must  be  capable  of 
so  modifying  this  configuration  as  to  make  it  acquire 
the  same  instinct  which  the  nervous  configuration  of 
the  parent  had  acquired  by  the  action  of  external 
influences. 

If  now  we  draw  a  conclusion  from  all  that  we  have 
said  thus  far,  we  can  very  well  assert  that  the  attempt 
to  account  by  means  of  the  centroepigenetic  hypothesis, 
for  the  Lamarckian  principle  in  all  its  manifold  and 
comprehensive  manifestations  has  not  failed.  One  notes 
also  that  this  hypothesis  can  be  assigned  to  the  class  of 
mnemonic  theories  of  heredity,  but  with  this  important 
difference,  that  the  theories  of  Haeckel,  Hertwig,  Orr, 
Cope,  and  other  similar  ones,  in  order  to  explain  the 
phenomenon  of  the  inheritance  of  acquired  characters 
appearing  during  development,  have  recourse  to  a  phe- 
nomenon still  more  special  and  more  complex,  the 
mnemonic,  and  therefore  do  not  and  cannot  constitute 
any  real  explanation.  Centroepigenesis  on  the  contrary, 
as  we  saw  utilizes  as  subordinate  hypothesis  a  very 
general  and  very  simple  biological  phenomenon,  which 
in  many  respects  indeed  is  like  certain  phenomena  of 
the  accumulation  of  energy  in  the  inorganic  world,  and 


Ontogenetic  and  Mnemonic  Phenomena          315 


which  would  be  at  the  same  time  the  basis  of  both  the 
phenomenon  of  heredity  and  the  mnemonic  phenomenon. 
So  that  these  latter  instead  of  being  explained  by  each 
other,  would  both  be  explained  by  this  single  phenome- 
non, more  simple  and  more  general  than  either. 

So  it  will  be  worth  while  for  us,  in  the  last  chapter 
which  follows  this,  to  subject  the  mnemonic  phenomenon 
to  a  rapid  examination  in  order  to  see  if  it  likewise 
really  finds  an  adequate  explanation  in  this  supposed 
elementary  biological  phenomenon  of  a  specific  accumu- 
lation of  energy.  And  then  we  shall  examine  more 
closely  the  question  whether  this  same  hypothetical  ele- 
mentary phenomenon  cannot  at  the  same  time  explain 
at  least  partially  the  fundamental  properties  of  the  vital 
phenomenon  itself  in  all  its  generality. 


CHAPTER  VIII 

THE  PHENOMENON  OF  MEMORY  AND  THE  VITAL 
PHENOMENON 

The  comparison  between  the  phenomena  of  develop- 
ment and  the  phenomena  of  memory  especially  after  the 
discovery  of  the  fundamental  biogenetic  law,  that  onto- 
geny is  a  recapitulation  of  phylogeny,  has  presented 
itself  spontaneously  to  a  large  number  of  authors. 
"The  germ,"  said  Claude  Bernard,  "seems  to  preserve 
the  memory  of  the  organism  from  which  it  came."230 
Haeckel  attributes  development  to  the  mnemonic  quality 
of  his  plastidules.  We  have  seen  in  the  sixth  chapter 
how  Orr  endeavored  to  explain  the  recapitulation  of 
phylogeny  during  ontogeny  by  the  mnemonic  law  of 
habit;  how  Cope  held  that  ontogeny  is  called  forth  by 
the  unconscious  memory  of  phylogeny;  how  Nageli  and 
in  some  places,  Hertwig  himself,  attributes  to  the  idio- 
plasm the  faculty  of  remembering,  so  to  speak,  the  suc- 
cessive stages  through  which  it  had  gradually  passed. 

But  by  far  the  boldest  contender  for  the  acceptance 
of  the  essential  likeness  of  the  ontogenetic  and  mnemonic 
phenomena  has  been  Hering:  "What  else  is  this  re- 
appearance in  the  developing  daughter  organism  of 
characters  of  the  parent  organism,  than  a  reproduction, 

280Claude  Bernard:  Lemons  sur  les  phenomenes  de  la  vie  com- 
muns  aux  animaux  et  aux  vegetaux.  P.  66. 


Likeness  of  Ontogeny  and  Memory  317 

on  the  part  of  organized  matter,  of  processes  in  which 
it  already  took  part  at  another  time,  even  if  only  as 
a  germ  in  the  ovary,  and  which  now  at  an  opportune 
moment  it  recalls  exactly  while  reacting  to  the  same  or 
similar  stimuli  in  a  way  similar  to  that  formerly  followed 
by  that  organism  of  which  it  was  once  a  part,  and 
whose  vicissitudes  it  then  had  shared?  If  the  parent 
organism  by  long  custom  or  repeated  action  has  changed 
somewhat  in  nature  in  such  a  way  that  the  germinal 
cellule  within  it  has  also  been  affected  however 
feebly  it  may  be,  and  if  this  latter  commences  a 
new  existence  growing  and  developing  into  a  new  being 
of  which  the  different  parts  are  yet  only  itself  and  flesh 
of  its  flesh;  and  if  in  thus  developing  it  reproduces  that 
experience  which  it  had  already  shared  at  another  time 
as  part  of  a  great  whole;  this  is  indeed  just  as  astonishing 
as  when  the  memory  of  his  earliest  childhood  suddenly 
comes  back  to  the  old  man,  but  it  is  no  more  astonishing. 
And  whether  it  is  still  the  same  organized  substance 
which  reproduces  a  process  already  once  experienced, 
or  whether  it  is  only  a  descendant,  a  portion  of  itself, 
which  in  the  interval  has  grown  and  become  large,  this 
is  manifestly  a  difference  of  degree  only  and  not  of 
essence."  231 

We  shall  not  repeat  here  the  objections  which  have 
been  advanced  against  the  similar  affirmations  of  Orr 

231Ewald  Hering:  Uber  das  Gedachtnis  als  eine  allgemeine 
Funktion  der  organisierten  Materie.  Wien,  Gerold,  1876.  P.  16 — 17. 
Hering's  thesis  has  recently  been  taken  up  again  by  Richard  Semon 
and  been  treated  more  thoroughly  and  completely  in  his  work :  Die 
Mneme  als  erhaltendes  Prinzip  im  Wechsel  des  organischen  Gesche- 
hens.  Leipzig,  Engelmann,  1904.  (See  Eugenio  Rignano :  Une 
nouvelle  theorie  mnemonique  du  developpement.  Revue  Philoso- 
phique.  Paris,  Alcan,  November  1906.  No.  n.) 


318  The  Mnemonic  Phenomenon 

and  Cope.  Only  it  may  be  noted  once  again  that  the 
absence  of  any  analysis,  however  conjectural,  of  the 
nature  of  the  phenomena  of  memory  makes  the  explana- 
tion of  development  which  Hering  tried  to  give  in  this 
way,  not  only  quite  indefinite  and  nebulous,  but  also 
gives  it  the  appearance  of  a  quite  artificial  comparison 
between  processes  much  too  unlike. 

The  same  is  true  in  a  yet  greater  degree  of  the  general 
theory  of  Hering  of  which  development  is  a  particular 
case,  and  which  considers  memory  a  general  function 
of  all  living  organized  matter.  Ribot  accepts  this  theory 
and  modifies  it  in  that  he  expresses  the  view  that  "mem- 
ory is  essentially  a  biological  phenomenon  and  only 
accidentally  a  psychological  one." 232 

This  extension  of  the  mnemonic  faculty  over  every 
vital  phenomenon  without  exception,  though  it  contains 
much  truth,  cannot  by  itself  constitute  any  explanation 
of  either  one  phenomenon  or  the  other,  but  rather  helps 
to  plunge  both  into  greater  obscurity;  for  while  by  this 
comparison  the  obscure  fundamental  peculiarities  com- 
mon to  both  become  in  no  wise  clearer,  one  loses  sight 
of  those  most  familiar  and  characteristic  properties  which 
are  different  in  the  two  phenomena,  and  which  are  the 
ones  which  have  served  to  give,  up  to  the  present  day, 
the  most  correct  idea  possible  of  both. 

The  mnemonic  phenomenon  can  serve  then  neither 
as  an  explanation  of  the  phenomena  of  development  nor 
of  vital  phenomena  in  general,  because  it  is  as  we  said 
a  phenomenon  even  more  special  and  more  complex  than 
those  which  it  has  been  summoned  to  explain.  Never- 
theless there  may  yet  be  the  possibility  that  the  resem- 

282Ribot :  Les  maladies  de  la  memoire.    Paris,  Alcan,  1901.  P.  i. 


Specific  Mnemonic  Elements  319 

blance  which  appears  to  exist  between  some  of  the 
essential  properties  of  these  three  phenomena  may  be 
explained  by  a  still  more  general  and  more  simple 
phenomenon  which  would  form  the  common  basis  of  all 
three  categories  of  phenomena;  the  ontogenetic,  the 
mnemonic  properly  so  called  or  psycho-mnemonic,  and 
the  vital. 

We  have  already  shown  that  this  common  phe- 
nomenon might  perhaps  be  implied  in  the  hypothesis 
set  forth  above,  in  which  we  regarded  the  specific  potential 
elements  as  accumulators  of  specific  nervous  energy  or 
as  specific  elementary  accumulators.  In  just  this  capacity 
of  restoring  again  the  same  specificity  of  nervous  current 
as  that  by  which  each  element  had  been  deposited  one 
would  look  for  the  cause  of  the  mnemonic  faculty  in  the 
widest  sense,  which  all  living  matter  possesses.  And 
further  the  very  essence  of  the  mnemonic  faculty  would 
consist  entirely  in  this  restitution. 

It  may  be  remarked  here  that  the  specific  potential 
elements  which  as  we  saw  in  the  preceding  chapter  could 
be  called  also  specific  elementary  accumulators  are  thus 
susceptible  now  of  receiving  a  third  name,  namely  that 
of  mnemonic  elements. 

According  to  this  definition,  ordinary  electric  accumu- 
lators, which  are  as  we  saw  merely  generic  accumulators, 
represent,  one  may  say,  only  very  imperfect  mnemonic 
elements.  On  the  contrary  the  more  capable  they  were 
of  storing  up  each  a  single  one  of  the  innumerable  minute 
specific  variations  of  such  an  energy  and  of  reproducing 
it  identically  at  each  discharge,  the  more  perfect 
mnemonic  elements  they  would  become. 

As  of  all  the  vital  phenomena  the  psycho-mnemonic 
are  those  which  present  most  distinctly  the  mnemonic 


320  The  Mnemonic  Phenomenon 

faculty  possessed  by  all  living  substance,  it  is  in  them 
that  we  shall  be  able  best  to  verify  the  laws  which  be- 
come impressed  upon  this  mnemonic  faculty  through  the 
conception  that  it  is  based  upon  the  specific  accumula- 
tion and  reproduction  suggested  above.  And  the  most 
important  of  these  laws  have  just  been  briefly  outlined 
in  the  preceding  chapters. 

Of  the  three  elements  of  memory:  the  preservation 
of  certain  states,  their  reproduction,  and  their  localization 
in  the  past,  Ribot  thinks  that  the  first  two  alone  are 
necessary  and  characteristic.233  We  can  note,  that  the 
hypothesis  of  mnemonic  elements  permits  us  to  conceive 
of  this  preservation  of  certain  states  as  an  accumulation 
of  specific  energy  and  their  reproduction  as  the  discharge 
of  that  specific  energy. 

"When  we  speak,"  writes  Maudsley,  "of  a  trace,  or 
vestige  or  residuum  all  we  mean  to  imply  is  that  an 
effect  is  left  behind  in  the  organic  element,  a  something 
retained  by  it  which  disposes  it  to  a  similar  functional 
act;  a  disposition  has  been  acquired  which  differentiates 
it  henceforth,  although  we  have  no  reason  to  think  that 
there  was  any  original  specific  difference  between  one 
nerve  cell  and  another." 234  This  something  which 
leaves  an  impression  after  it  in  the  nerve  cell  and  which 
disposes  it  to  other  similar  functional  acts  will  be  to  our 
mind,  a  true  and  real  material  residue  of  substance 
capable  of  reproducing  the  same  functional  current  as 
that  by  which  it  had  been  deposited.  And  the  differ- 
entiation of  nerve  cells,  as  indeed  of  all  other  somatic 
cells,  consists  in  the  acquisition  by  each  of  them  of  a 

""Ribot:    Ibid.    P.  2. 

23*Maudsley:  The  Physiology  of  Mind.  Third  edition.  Lon- 
don, Macmillan,  1876.  P.  270. 


Psycho-mnemonic  Phenomena  321 

greater  or  less  number  of  specific  or  mnemonic  potential 
elements  differing  from  one  cell  to  another.  But  we 
must  bear  in  mind  that  this  differentiation  is  not  acquired 
exclusively  after  birth,  but  appears  already  within  cer- 
tain limits,  at  least  in  relation  to  all  the  congenital 
instincts,  during  ontogeny. 

"We  see,"  writes  Hering,  "how  an  entire  group  of 
sensations  become  reproduced  with  such  vividness  and 
in  such  precise  order  of  space  and  time  that  it  can 
deceive  us  as  to  its  reality.  This  shows  us  in  a  most 
striking  way  that  even  after  the  sensation  and  percep- 
tion in  question  has  long  since  disappeared,  there  remains 
still  in  our  nervous  system  a  material  trace,  an  alteration 
of  the  molecular  or  atomic  connections  by  which  the 
nervous  substance  is  rendered  capable  of  reproducing 
these  physical  processes,  with  which  the  corresponding 
psychic  process  of  sensation  and  perception  is  also  deter- 
mined."— "The  representations  do  not  last  as  representa- 
tions but  what  does  persist  is  that  particular  attunement 
of  the  nervous  substance,  by  virtue  of  which  when  it 
is  properly  struck  it  sounds  again  today  the  same  note 
which  it  gave  forth  yesterday."  235 

This  conception  of  Hering  of  the  disposition  of  the 
nervous  substance  to  sound  again  the  tone  of  yesterday 
is  derived  from  the  physical  phenomenon  of  acoustic 
resonators.  The  nervous  substance  which  would  be  made 
to  vibrate  in  a  given  specific  way  at  a  given  point  by  a 
definite  elementary  sensation  or  representation  would  re- 
main from  that  moment  capable  of  vibrating  always  and 
exclusively  according  to  that  specific  mode.  According 
to  the  hypothesis  of  mnemonic  elements  on  the  contrary, 

'"Hering :    tlber  das  Gedachtnis  etc.    P.  8,  9. 


322  The  Mnemonic  Phenomenon 

it  is  well  to  repeat  again,  each  elementary  sensation  or 
representation  would  consist  not  so  much  in  a  specific 
vibration  of  the  nervous  substance  at  this  or  that  point 
as  in  the  production  by  the  action  of  external  stimuli 
of  a  given  specific  nervous  current.  In  this  way  the 
memory  of  an  elementary  sensation  or  representation 
would  consist  only  in  the  reproduction,  by  the  action  of 
causes  now  internal,  of  the  same  specific  nervous  current. 
In  other  words  the  wray  in  which  the  hypothesis  of 
mnemonic  elements  or  specific  elementary  accumulators 
would  conceive  of  the  mnemonic  phenomena  is  as 
follows : 

A  series  of  sounds  or  of  words,  for  example  a  certain 
melody,  or  some  phrase  of  a  discourse,  when  once  it  has 
entered  by  the  ear,  we  can  imagine,  produces  a  series 
of  nervous  currents  in  the  auditory  nerve  specifically 
different  from  one  another,  just  as  in  a  telephone  the 
successive  electric  currents  are  specifically  different  from 
one  another  (in  this  particular  case  different  in  intensity) 
which  the  same  series  of  sounds  produces  in  the  receptive 
apparatus  and  later  transmits  along  the  wire.  If  then 
one  or  several  nerve  centers,  after  receiving  these  spe- 
cifically different  currents,  are  capable  of  storing  up  these 
specific  energies,  each  distinct  from  the  other,  and  to 
reproduce  them  unaltered  later  at  the  moment  of  dis- 
charge, and  if,  further,  the  discharge  of  each  immediately 
preceding  specific  energy  and  it  alone  is  capable  of  pro- 
ducing the  liberation  of  the  specific  energy  immediately 
following,  (and  we  have  seen  above  that  this  is  one 
consequence  of  the  hypothesis  of  specific  elementary 
accumulators),  it  will  be  in  this  way  possible  for  the 
same  succession  of  different  ideas  or  impressions  to  be 


Psycho-mnemonic  Phenomena  323 

repeated  a  great  number  of  times  and  it  is  in  just  this 
that  the  mnemonic  phenomenon  consists. 

One  could  evidently  say  the  same  thing  of  the  optic 
phenomenon,  that  is  to  say,  of  any  series  of  colors  or 
specific  luminous  vibrations  which  succeed  one  another 
in  space  or  time. 

Ribot  has  rightly  said  that  "There  is  not  one  memory, 
but  memories;  that  there  is  not  one  seat  of  memory, 
but  particular  seats  for  each  particular  memory." 23Q 
And,  according  to  our  theory,  each  mnemonic  element 
would  just  constitute  a  particular  seat  for  each  elementary 
sensation  or  each  particular  specific  impression. 

In  this  sense  also,  that  is  to  say  on  the  condition 
that  the  expression  "nervous  elements"  be  not  disjoined 
from  the  conception  of  elementary  specific  accumulators 
or  mnemonic  elements,  we  can  accept  the  idea  of  memory 
which  this  investigator  (Ribot)  has  put  forward:  "If 
we  attempt,"  writes  he,  "to  conceive  a  good  memory  and 
to  express  this  in  physiological  terms,  we  must  figure 
to  ourselves  a  great  number  of  nervous  elements,  each 
modified  in  a  particular  manner,  each  taking  part  in  one 
combination  and  probably  capable  of  entering  into  sev- 
eral. Memory  has  then  static  and  dynamic  bases.  Its 
strength  is  in  relation  to  their  number  and  stability."  237 

"It  has  been  asked,"  continues  Ribot,  "if  each  nerve 
cell  can  preserve  several  different  modifications  or  if 
once  modified  it  is  forever  polarized.  The  number  of 
cerebral  cells  being  about  600,000,000  according  to  the 
calculations  of  Meynert  (and  Sir  Lionel  Beale  gives  a 
much  higher  figure)  the  hypothesis  of  a  single  impression 


2S8Ribot:    Les  maladies  de  la  memoire.     P.  n. 
Ribot :    Ibid.    P.  32. 


237 


324  The  Mnemonic  Phenomenon 

is  not  inconceivable."  238  It  may  be  remarked  here  that 
according  to  the  hypothesis  of  mnemonic  elements  there 
is  room  in  each  brain  cell  for  a  whole  series  of  specific 
deposits  and  not  merely  for  one  specific  deposit.  Indeed 
we  must  suppose,  as  we  have  seen,  that  the  germ  sub- 
stance contains  a  very  great  number  of  specific  potential 
or  mnemonic  elements,  and  we  can  also  assume  that  the 
same  is  true  of  the  very  complex  mnemonic  centers. 

Provisionally  it  can  be  affirmed  that  the  close  depend- 
ence of  memory  upon  the  nutritive  processes,239  indicates 
strongly  that  the  preservation  of  memories  is  to  be 
ascribed  to  accumulations  of  substance.  Further,  as  was 
very  well  remarked  by  Hensen,  the  fact  that  many  mem- 
ories may  remain  entirely  dormant  throughout  several 
years,  and  then  can  come  again  with  great  distinctness 
into  consciousness,  notwithstanding  that  all  the  parts  of 
the  organism  have  been  renewed  several  times  in  the 
interval,240  indicates,  (if  one  recollects  that  assimilation 
consists  in  the  incessant  reproduction  of  new  masses, 
always  of  identically  the  same  substance),  that  in  order 
to  preserve  these  memories  it  is  sufficient  if  for  one  given 
substance  there  be  substituted  another  identical  one. 

If  it  appears  thus  to  be  shown  by  facts,  that  the 
preservation  of  memories  is  due  to  accumulation  and 
conservation  of  substance,  a  whole  series  of  other  facts 
seems  to  demonstrate  that  the  reawakening  of  these 
memories  consists  in  the  restitution  of  the  same  currents 
as  had  formerly  constituted  the  actual  sensation  or 
impression. 

238Ribot :    Ibid.    P.  17. 
238Ribot :    Ibid.    P.  155—163. 

240Hensen:  tJber  das  Gedachtnis.  Kiel,  Universitats-Buchhand- 
lung,  1877.  P.  13. 


Physiological  Effects  of  Memories  325 

We  need  not  recall  here  all  the  innumerable  examples 
which  show  that  the  motor  or  secretory  or  in  general 
the  physiological  effects  of  the  mnemonic  reawakening 
of  a  given  sensation  or  impression  are  quite  identical 
with  those  of  the  real  sensation  or  impression:  for 
example,  the  recollection  of  a  certain  dish  produces  the 
same  salivation  as  is  provoked  by  the  dish  itself;  the 
memory  of  the  beloved  person  can  cause  each  time  the 
same  reddening  of  the  countenance,  the  same  brightening 
of  the  eyes,  the  same  acceleration  of  the  pulse  as  the 
direct  view  of  that  person;  every  time  that  a  mother 
thinks  of  her  nursing  child  there  comes  a  flow  of  milk 
into  the  breasts.241  These  are  some  examples  which  show 
the  substantial  identity  of  the  functional  and  mnemonic 
stimulus. 

Here  we  should  like  to  cite  just  the  following  experi- 
ment of  Wundt  mentioned  by  Ribot:  "If,  after  looking 
for  a  long  time  at  a  picture  with  very  vivid  colors,  we 
keep  the  picture  before  our  minds  with  the  eyes  closed 
and  after  that  suddenly  open  the  eyes  and  fix  them  upon 
a  white  surface,  we  see  there  the  picture  which  we  had 
kept  in  our  minds,  but  in  the  complementary  colors.  This 
fact,  remarks  Wundt,  proves  that  the  nervous  operation 
is  the  same  in  the  two  cases,  in  the  perception  and  in  the 
memory/'  242  According  to  our  view  this  indicates  that 
the  nerve  current  which  corresponds  to  the  color,  let 
us  say  red,  of  the  picture,  and  reproduced,  together  with 
all  other  currents  corresponding  to  the  other  special 
characters  of  this  picture,  by  the  mnemonic  center 
recalling  it  again,  is  equal  but  opposite  in  direction  to 
that  current  which  the  red  rays  coming  from  the  white 

241Lewes:    The  physical  basis  of  mind.     P.  288. 
242Ribot:    Ibid.    P.  ii. 


326  The  Mnemonic  Phenomenon 

surface  send  toward  the  center :  Consequently  only  the 
currents  sent  by  complementary  rays  from  this  white 
surface  can  reach  that  center,  and  these  combined  with 
the  currents  corresponding  to  the  other  characters  of 
the  picture  must  give  it  the  same  aspect  as  before  only 
with  a  complementary  color. 

If  the  preservation  of  each  memory  is  due  to  deposits 
exactly  equal  in  number  to  the  specific  elementary  ner- 
vous currents  which  the  sensation  or  complex  impression 
had  provoked  in  the  nervous  system,  we  are  then  in  a 
position  to  comprehend  also  the  phenomenon  known 
under  the  name  of  abridgment.  "Every  memory,"  says 
Ribot,  "however  clear  it  may  be,  undergoes  an  enormous 
abridgment.  The  farther  the  present  recedes  into  the 
past,  the  more  do  the  states  of  consciousness  diminish 
and  disappear.  Reviewed  at  several  days  distance  there 
remains  little  or  nothing  of  them;  for  the  most  part 
they  have  darkened  into  a  nothingness  from  which  they 
will  never  again  emerge  and  have  taken  with  them  the 
time  duration  inherent  in  them.  Consequently  a  diminu- 
tion of  the  states  of  consciousness  is  a  diminution  in 
time."  243 

This  disappearance  of  the  elementary  states  of  con- 
sciousness producing  the  abbreviation  of  memory  will 
be  due  then,  according  to  our  view,  to  the  disappearance 
of  the  secondary  mnemonic  elements,  that  is  to  say  those 
provided  with  a  minimum  quantity  of  the  respective 
substance,  (and  of  the  potential  energy  which  is  the  con- 
sequence of  it),  from  the  series  which  constitutes  the 
entire  memory.  Possibly  this  disappearance  can  be 
caused  by  the  fact  that  the  nutritive  fluid  has  come 

248Ribot:   Ibid.    P.  44,  45. 


Abridgment  in  Memory  and  Ontogeny          327 

gradually  to  be  entirely  absorbed  by  the  principal 
mnemonic  elements  of  the  same  series  and  by  the  new 
elements  which  later  supervene  as  a  consequence  of  later 
sensations  also  stored  up  in  memory. 

Let  us  note  that  this  abridgment  of  every  memory, 
interpreted  as  above,  becomes  then  completely  capable 
of  explaining  also  the  similar  abridgment  which  phy- 
logeny  undergoes  during  ontogeny.  In  fact,  of  the 
ancient  mnemonic  elements  constituting  the  germinal 
substance,  the  most  pronounced,  that  is  those  which  are 
represented  by  the  largest  quantity  of  substance,  will 
alone  persist.  The  less  pronounced  ancient  mnemonic 
elements,  the  total  quantity  of  nourishment  for  all 
mnemonic  elements  remaining  the  same  or  varying  only 
within  definite  limits,  will  have  all  their  portion  of 
nourishment  taken  away  by  the  more  pronounced  ancient 
mnemonic  elements,  and  by  the  new  mnemonic  elements 
whose  number  will  continually  increase  with  each  phy- 
logenetic  advancement.  Not  being  able  consequently  to 
regain  their  substance  completely  in  each  ontogeny  they 
will  gradually  disappear. 

If  we  have  always  supposed  so  far,  as  the  first  degree 
of  approximation  necessary  to  the  comprehension  of  the 
fundamental  nature  of  the  phenomenon,  that  ontogeny 
reproduces  phylogeny  entirely,  these  abridgments  of 
memory  permit  us  then  to  penetrate  still  farther  into 
the  inner  nature  of  this  phenomenon  and  to  recognize 
that  ontogeny  instead  of  being  an  entire  reproduction 
of  phylogeny  can  be  only  a  succinct  recapitulation. 

In  recalling  a  given  memory  the  mnemonic  cells  do 
not  lose  the  "impression"  as  we  call  it  which  they 
preserve  of  that  memory;  on  the  contrary  the  more  a 
memory  is  recalled  the  more  the  respective  "impression" 


328  The  Mnemonic  Phenomenon 

is  reinforced.  This  signifies  that  the  activation  of 
mnemonic  elements  or  the  performance  of  their  func- 
tion merely  causes  their  mass  and  their  potential  energy 
to  increase.  This  fact,  that  the  active  participation  of 
the  mnemonic  centers  in  the  biological  phenomena  of 
memory  leaves  them  unaltered  in  the  same  state  as 
before,  so  that  they  are  just  as  capable  and  even  more 
capable  than  formerly  of  reproducing  many  more  times 
the  same  phenomena,  reveals  them  to  us  in  this  relation 
also  as  entirely  similar  in  nature  to  the  germinal  sub- 
stance, which  active  participation  in  the  biologic  phe- 
nomena of  ontogeny  leaves  likewise  in  the  same  state 
as  before  and  even  renders  always  more  capable  of  again 
producing  the  phenomenon  of  ontogeny. 

According  to  the  centroepigenetic  hypothesis  the 
mnemonic  elements  of  the  germinal  substance,  with  the 
exception  of  the  last  belonging  to  the  adult  stage,  can 
become  active  only  at  each  new  ontogenesis ;  that  is  their 
reawakening  would  take  place  only  after  long  periods 
of  repose  which  might  last  even  through  several  years. 
Such  reawakening  of  mnemonic  centers  at  long  inter- 
vals of  years  constitutes  a  very  ordinary  phenomenon. 
Cases  are  frequent,  for  example,  of  adults  who  are  able 
to  repeat  poetry  which  they  had  learned  in  their  earliest 
childhood,  even  after  many  years  during  which  they  have 
never  had  occasion  to  repeat  it  at  any  time.  Coleridge 
speaks  of  a  young  girl  who,  in  the  delirium  of  fever, 
repeated  long  pieces  in  the  Hebrew  tongue  which  she 
did  not  understand,  but  which  she  had  heard  read  aloud 
a  very  long  time  before  by  a  priest  in  whose  service  she 
had  been.244  A  Lutheran  preacher  of  German  origin 

244Maudsley:    The  physiology  of  mind.     P.  25. 


Persistence  of  Conditions  Latent  in  Memory      329 

living  in  America  who  had  in  his  congregation  a  con- 
siderable number  of  Germans  and  Swedes  related  to 
Dr.  Rush  that  nearly  all  a  little  before  dying  pray  in 
their  mother  tongue.  "I  have,"  said  he,  "innumerable 
examples  of  it  and  among  them  several  in  which  I  am 
sure  they  had  not  spoken  German  or  Swedish  for  fifty 
or  sixty  years/'  245 

The  following  two  facts  are  still  more  typical: 

A  lady  in  the  last  stages  of  a  chronic  disease  was 
taken  from  London  to  the  country.  Her  little  daugh- 
ter, who  had  not  yet  learned  to  talk,  was  sent  to  her 
and  after  a  short  visit  was  sent  back  to  the  city.  The 
lady  died  several  days  later.  The  daughter  grew  up 
to  maturity  without  remembering  her  mother.  She  had 
then  occasion  to  see  the  room  in  which  her  mother  died. 
Although  ignorant  of  that  fact,  upon  entering  the  room 
she  started,  and  when  asked  the  cause  of  her  emotion, 
she  said  "I  have  a  distinct  impression  of  having  been 
in  this  room  before.  There  was  in  that  corner  a  lady 
in  bed,  apparently  very  ill,  who  leaned  over  me  and 
wept."  246 

Similarly,  a  man  of  very  marked  artistic  tempera- 
ment, as  soon  as  he  came  in  front  of  a  castle  in  Sussex 
had  an  extremely  vivid  impression  of  having  already 
seen  it,  and  he  recalled  in  his  imagination  the  procession 
of  visitors  in  all  its  details.  He  learned  from  his  mother 
that  he  had  actually  been  brought  there  on  an  excursion 
at  the  age  of  sixteen  months  and  that  the  recollection 
which  he  had  of  the  visit  was  very  exact.247 

These  examples  show  then  how  remarkable  can  be 

24BRibot :    Les  maladies  de  la  memoire.     P.  146 — 147. 
246Ribot:    Ibid.    P.  143—144. 
247Ribot:    Ibid.    P.  144. 


330  The  Mnemonic  Phenomenon 

the  persistence  of  conditions  latent  in  memory.  Let  us 
note  further,  that  these  last  two  cases  present  in  a  very 
striking  form  one  of  those  "revivifications  of  memory 
through  contiguity  in  space,"  as  Ribot  would  call  them. 

This  reawakening  of  memory  through  contiguity  in 
space  is  only  a  particular  case  of  the  general  law  of  the 
association  or  succession  of  ideas.  They  indicate  that 
the  mnemonic  center  becomes  active  only  when  the  sight 
of  the  same  place  induces  in  the  environment  of  that 
center  almost  the  same  state  of  distribution  of  nervous 
energy  as  was  present  at  the  former  time  when  it  received 
the  impression.  That  is  exactly,  as  we  have  seen  in 
the  preceding  chapter,  the  immediate  result  of  the  hypoth- 
esis of  specific  elementary  accumulators  there  advanced. 

In  the  mnemonic  phenomena  properly  so  called,  it 
is  the  infinitely  diverse  and  constantly  changing  condi- 
tions of  the  outer  world  and  the  corresponding  sensa- 
tions following  in  the  individual  which  call  forth  like 
a  phantasy  such  and  such  an  association  or  succession 
of  ideas.  But  in  the  development  of  the  embryo  which 
is  removed  from  the  action  of  every  external  perturbing 
influence  and  above  all,  which  is  provoked  by  the  acti- 
vation of  different  specific  germinal  elements  from  one 
and  the  same  complex  mnemonic  center  constituted  by 
the  germinal  substance,  the  succession  of  mnemonic  states 
of  this  latter  called  into  activity  one  after  the  other  and 
of  the  corresponding  stages  of  ontogeny  must  inevitably 
proceed  in  an  uninterrupted  series,  always  the  same  for 
all  individual  ontogenies  of  the  same  species.  For  to 
reawaken  each  mnemonic  element  of  this  germinal  sub- 
stance there  must  again  concur  exactly  and  exclusively 
those  conditions  of  distribution  of  nervous  energy  in 


Succession  of  Ontogenetic  Mnemonic  States      331 

the  embryo  which  had  been  provoked  by  the  reawaken- 
ing of  the  mnemonic  element  immediately  preceding. 

It  is  then  in  development  even  more  than  in  mnemonic 
phenomena  properly  so  called  that  there  operates  the  law 
of  rigorous  succession,  in  which,  as  Ribot  says,  each 
member  of  a  series  "suggests"  the  following.248 

In  summing  up  all  that  we  have  said  thus  far  we 
can  thus  affirm  that  if  the  mnemonic  phenomena,  prop- 
erly so  called,  cannot  serve  to  explain  ontogenetic  phe- 
nomena nor  the  latter  to  explain  the  former,  their 
resemblance  which  has  nevertheless  been  noted  by  so 
great  a  number  of  authors  can  be  explained  by  a  third 
phenomenon  more  general  and  more  simple  than  either. 
And  this  phenomenon  consists  in  the  faculty  possessed 
by  all  living  substance  of  accumulating  and  giving  back 
again  individually  the  different  particular  specificities  of 
generic  nervous  energy,  which  constitutes  the  essence  of 
all  vital  phenomena  whatever. 

#  #  #  *  *  *  * 

This  property  of  accumulating  and  giving  back  spe- 
cific nervous  energy,  attributed  by  hypothesis  to  all  living 
organic  substance,  is  thus  shown  to  be  capable  of  explain- 
ing the  most  fundamental  biological  phenomena,  from 
histologic  specialization  of  cells  which  respond  always 
in  their  customary  specific  manner  no  matter  how  unusual 
may  be  the  stimulus  which  excites  them,  to  the  inheritance 
of  acquired  characters,  from  the  evolution  of  species 
and  the  repetition  of  phylogeny  by  ontogeny,  direct  con- 
sequences of  that  inheritance,  to  mnemonic  phenomena 
properly  so  called. 

It  remains  for  us  to  demonstrate  that  this  property, 

248Ribot:     Les  maladies  de  la  memoire.     P.  8. 


332  The  Vital  Phenomenon:  Assimilation 

as  we  have  affirmed  before,  can  help  to  explain  in  great 
part  the  essential  character  of  the  vital  phenomenon  itself 
in  all  its  generality — that  is  assimilation. 

The  fact  that  strikes  us  first  of  all  is,  that  the  vital 
phenomenon  depends  upon  continual  reproduction,  for 
assimilation  constantly  reproduces  the  substance  which  is 
gradually  consumed.  It  is  to  be  expected  therefore,  that 
if  there  are  any  fundamental  properties  of  living  organic 
substance  which  explain  the  phenomena  of  development 
or  of  reproduction  in  general,  they  must  then  be  capable 
of  accounting  for  assimilation  also,  inasmuch  as  it  is 
itself  a  phenomenon  of  reproduction. 

That  being  granted  it  will  be  worth  while  that  we 
next  stop  for  an  instant  to  take  a  look  at  and  consider 
briefly  a  few  of  the  principal  conceptions  which  biologists 
have  put  forward  on  the  nature  of  either  the  vital  phe- 
nomen  or  of  assimilation,  and  which  are  of  the  greatest 
interest  from  our  point  of  view. 

Roux,  for  example,  rightly  urges  that  the  nature  of 
life  must  be  dynamic.  "Life  is  in  its  essence  a  process, 
and  cannot  therefore  have  a  static  definition.  It  is 
therefore  only  a  processive  and  consequently  functional 
definition  which  can  approximate  the  essence  of  organic 
life."  249 

On  the  other  side  we  have  already  seen  the  reasons 
for  concluding  that  the  essence  of  the  vital  phenomenon 
consists  in  an  activation  of  nervous  energy.  We  re- 
call that  according  to  Orr  for  example,  the  funda- 
mental property  of  living  substance  is  an  "elemental 
nervousness."  25° 

248Roux :    tlber  die  Bedeutung  der  Kernteilungsfiguren.   Leipzig, 
Engelmann,  1883.  P.  18.  Gesamm.  Abhandl.  Bd.  II.  P.  142. 
260Orr :   A  Theory  of  Development  and  Heredity     P.  86. 


Conceptions  of  Vital  Energy  Reviewed  333 

We  have  already  seen  also  that  Claude  Bernard,  in 
agreement  with  that,  considers  the  sensibility  of  the  ner- 
vous substance  as  nothing  else  than  a  particular  modality 
of  irritability,  which  would  be  a  general  property  of 
all  living  substance.  "Sensibility,"  writes  he,  "considered 
as  a  property  of  the  nervous  system,  is  only  a  higher 
degree  of  a  simpler  property  which  exists  everywhere 
in  all  living  substance  both  animal  and  vegetable.  It 
has  nothing  essential  or  specifically  distinct.  It  is  the 
special  irritability  of  the  nerve  just  as  the  property  of 
contraction  is  the  special  irritability  of  the  muscle,  and 
as  the  property  of  secretion  is  the  special  irritability  of 
the  glandular  element.  These  phenomena  are  so  many 
different  degrees  of  one  and  the  same  elementary  phe- 
nomenon/' 251 

Bard  also  remarks  that  if  the  nature  of  the  energy 
constituting  the  basis  of  all  vital  phenomena  must  be 
single,  the  infinitely  varied  modalities  which  the  same 
vital  phenomena  present  must  then  be  due  to  as  many 
corresponding  modalities  of  this  single  energy. 

"In  spite  of  the  complexity  and  multiplicity  of  physio- 
logical functions,"  he  writes,  "it  is  possible  to  refer  them 
fundamentally  to  a  general  function  of  the  living  cell, 
namely  the  function  of  producing  derived  substances. 
Cellular  specificity  can  be  explained  and  made  compre- 
hensible only  as  this  single  function  is  able  to  insure  the 
innumerable  functions  necessary  for  an  entire  organism. 
The  variety  of  derived  substances  is  itself  the  effect  and 
the  proof  of  the  radically  different  vital  properties  of 
the  kinds  of  cells  which  create  each  of  them." 

"It  is  necessary  to  establish  an  essential  difference 

281  Claude  Bernard:  Legons  sur  les  phcnomenes  de  la  vie  com- 
muns  aux  animaux  et  aux  vegetaux.  P.  289 — 290. 


334  The  Vital  Phenomenon:  Assimilation 

between  the  physico-chemical  properties  of  the  derived 
substances  created  by  the  specific  activity  of  each  living 
cell,  and  the  properties  of  the  cell  nuclei  which  spring 
directly  from  the  special  forces  which  constitute  life. 
The  specific  differences  result  from  the  very  modality 
of  the  cell  life.  Cell  life  is  a  special  property  of  matter 
which,  like  all  its  highest  properties,  undoubtedly  con- 
sists in  a  particular  mode  of  movement.  One  can  say 
in  some  measure  that  the  cell  is  a  circuit  of  life.  Further 
vital  force,  like  light  or  electricity,  with  which  one  can 
compare  it,  not  so  much  to  show  that  it  is  very  similar 
to  them  as  to  facilitate  the  comprehension  of  it,  presents 
multiple  varieties  due  to  variations  of  wave  lengths,  of 
their  rythm,  direction,  or  of  any  other  element  of  this 
movement  which  one  could  suppose  or  discover.  These 
variations  are  without  doubt  incomparably  more  numer- 
ous than  those  of  electricity,  which  are  limited  enough, 
than  those  even  of  light,  which  are  certainly  infinitely 
more  numerous.  And  just  as  colors  indicate  the  differ- 
ences of  the  different  kinds  of  light,  so  the  different 
physiological  functions  of  species  of  cells  indicate  differ- 
ent modalities  of  life."  252 

It  is  worth  while  to  stop  a  moment  here,  to  show 
in  this  connection  how  readily  biologists  are  inclined  to 
fall  into  two  opposite  exaggerations. 

Some  deny  flatly  the  possibility  of  ever  arriving  at 
an  understanding  of  the  nature  of  life.  But  if  we  ask 
ourselves  in  what  this  understanding  of  the  nature  of 
life  could  consist,  from  the  point  of  view  of  positive 
philosophy,  we  have  no  difficulty  in  recognizing  that 

2B2Bard:  La  specificite  cellulaire  et  ses  principales  consequences. 
La  semaine  medicale.  Paris,  10.  March  1894.  P.  116. 


Understanding  of  the  Nature  of  Life  335 

such  an  understanding  must  be  reduced  to  comparing1 
vital  phenomena  with  some  physico-chemical  model  al- 
ready known,  suitably  modified  by  the  particular  special 
conditions  imposed  upon  it  so  that  just  these  special  con- 
ditions shall  determine  the  differences  which  exist  be- 
tween this  vital  phenomenon  and  the  phenomenon  of  the 
inorganic  world  most  closely  related  to  it.  If  this  be 
so,  it  is  then  the  duty  of  science  emphatically  to  reject 
such  a  denial  of  scientific  thought  as  the  renunciation 
of  the  quest  of  this  understanding  would  constitute. 
Whether  one  clearly  recognizes  it  or  not,  it  is  just  this 
search  for  the  nature  of  the  vital  principle  which  properly 
constitutes  the  principal  object  and  the  final  goal  of  all 
biologic  study  in  general. 

Others  again  are  not  willing  to  accord  to  life  even 
the  slightest  property  which  should  not  be  simply  physico- 
chemical  in  nature.  Among  all  these  it  is  enough  to 
cite  the  example  of  Verworn  who  not  only  relegates 
assimilation  to  the  category  of  purely  chemical  phe- 
nomena, by  means  of  his  "Biogen"  hypothesis,  but  who 
\vould  explain  protoplasmic  currents,  the  protusion  of 
pseudopodia,  the  movements  of  cilia,  and  in  general  all 
movements  of  living  beings  by  a  double  and  alternative 
chemotropism  of  protoplasmic  substance  rather  than  by 
currents  of  nervous  energy.  Protoplasmic  substance,  in 
fact,  according  as  it  remains  unstimulated  or  is  stimu- 
lated, that  is,  partially  decomposed  by  the  stimulus  which 
would  agitate  it  mechanically,  would  possess  a  chemical 
affinity  for  the  oxygen  of  the  environment  or  for  the 
substances  produced  by  the  nucleus  capable  of  rebuilding 
the  partially  decomposed  protoplasmic  substance.  And 
to  this  alteration  of  different  affinities,  the  opposite  proto- 


336          The  Vital  Phenomenon:  Assimilation 

plasmic  movements  of  expansion  and  contraction  would 
correspond.253 

Now  it  is  evident  that  this  endeavor  not  to  attribute 
to  vital  energy  any  specific  nature  of  its  own,  and  con- 
sequently to  explain  even  the  most  characteristic  phe- 
nomena of  life  by  means  of  only  those  energies  which 
physics  and  chemistry  afford  us  to-day,  can  have  no 
more  success  than  as  if  one  should  attempt  to  explain 
chemical  phenomena  by  means  of  physical  phenomena 
only.  For  the  conception  that  the  form  of  energy  on 
which  vital  phenomena  are  based  is  different  from  all 
forms  of  energy  which  have  hitherto  been  observed  in 
non-living  bodies,  has  absolutely  nothing  unscientific  in 
it,  any  more  than  the  conception,  for  example,  that  electri- 
city may  also  be  a  form  of  energy  different  from  all 
others. 

Vital  energy,  nervous  energy,  we  admit  at  once,  will 
certainly  be  a  particular  case  of  the  more  general  physico- 
chemical  forms  of  energy  already  known  or  yet  to  be 
known,  and  as  such  it  must  necessarily  be  subject  to 
the  laws  which  control  these  latter;  and  also,  a  fortiori, 
to  the  laws  which  control  all  energy  in  general.  But  even 
as  such,  that  is  as  a  particular  case  of  more  general, 
physico-chemical  forms  of  energy,  it  will  have  besides 
further  special  laws  of  its  own  which  are  only  experi- 
mentally to  be  determined  and  cannot  be  deduced  from 
the  more  general  laws  even  though  it  must  always  be 
subjected  to  them.  And  it  is  just  these  laws  of  its 
own  which,  out  of  a  physico-chemical  energy,  make  it 
vital  energy.  This  conception  has  led  us  to  attribute 
to  nervous  energy,  set  forth  as  the  basis  of  life,  special 

253Verworn:  Die  Biogenhypothese.  Jena,  Fischer,  1903;  and 
Die  Bewegung  der  lebendigen  Substanz,  especially  P.  100 — 103. 


Conceptions  of  Assimilation  Reviewed  337 

properties,  which  electric  energy,  in  certain  respects 
related  to  it,  does  not  possess. 

If,  passing  on  now  to  assimilation,  we  examine  the 
conceptions  which  the  biologists  have  formed  of  it,  we 
shall  see  that  their  opinions  on  that  subject  are  quite  re- 
markably concordant. 

Thus,  for  example,  Lewes  says:  "The  peculiarity 
of  vital  processes  consists  in  this,  that  living  matter  under- 
goes molecular  changes  of  composition  and  decomposition 
which  are  simultaneous,  and  by  this  simultaneity  it 
preserves  its  integrity  of  structure."254 

"Life,"  remarks  in  his  turn  Oscar  Hertwig,  "mani- 
fests itself,  expressed  in  the  most  general  terms,  in  this 
that  the  cell,  by  virtue  of  its  own  organization  and 
under  the  influences  of  the  external  world  undergoes 
continual  changes  and  develops  forces  whereby  its  organic 
substance,  on  the  one  hand  continually  destroyed  with 
determined  manifestations  of  energy  on  the  other  hand 
is  regenerated." — "The  life  process  depends  then,  on  a 
continual  destruction  and  reformation  of  organic  sub- 
stance." 255 

But  the  clearest  and  most  suggestive  of  all  is  Claude 
Bernard  in  the  following  celebrated  passage : 

"The  characteristics  of  life  considered  in  their  essence 
and  in  their  entirety  can  be  classed  in  two  groups." 

"i.  The  phenomena  of  consumption,  of  vital  de- 
struction, which  correspond  to  the  functional  phenomena 
of  the  organism." 

"2.     Plastic  phenomena  or  phenomena  of  vital  crea- 

2B4Lewes :    The  Physical  Basis  of  Mind.     P.  5. 
2BBOscar  Hertwig:   Die  Zelle  und  die  Gewebe.    Bd.  I,  P.  54,  and 
Bd.  II,  P.  190—191. 


338  Assimilation 

tion,  which  correspond  to  functional  repose  and  to  organic 
regeneration." 

"Everything  which  goes  on  in  the  living  being  is  in 
relation  to  one  or  other  of  these  types;  and  life  is  char- 
acterized by  the  union  and  combination  of  these  two 
orders  of  phenomena." 

"Disorganization  or  dis-assimilation  uses  up  living 
material  while  the  organs  perform  their  functions.  As- 
similative synthesis  regenerates  the  tissues.  It  reassem- 
bles the  reserve  materials  which  the  functioning  organism 
must  use  up.  These  two  processes  of  destruction  and 
renovation,  although  inverse,  are  absolutely  connected 
and  inseparable,  in  the  sense  at  least  that  destruction 
is  the  necessary  condition  of  renovation.  The  phenomena 
of  functional  destruction  are  themselves  the  precursors 
and  instigators  of  the  renewal  of  material  by  the  forma- 
tive process  which  is  accomplished  silently  in  the  interior 
of  the  tissues."  256 

Dastre  remarks  finally  that  "Claude  Bernard  devel- 
oped from  the  analysis  of  substances  excreted  as  the  result 
of  physiological  work,  his  conviction  that  every  mani- 
festation of  functional  phenomena  is  necessarily  asso- 
ciated with  some  organic  destruction.  For  excretions 
certainly  bear  witness  of  organic  demolition." 

"But  the  underlying  reason,"  continues  Dastre,  "of 
this  interdependence  between  chemical  destruction  and 
function  is  made  recognizable  by  energetics.  A  part  of 
the  organic  material  (reserve  material,  but  also  living 
protoplasm)  becomes  decomposed,  chemically  simplified, 
reduced  to  a  lower  degree  of  complexity,  and  abandons 

25cClaude  Bernard:  Legons  sur  les  phenomenes  de  la  vie  com- 
muns  aux  animaux  et  aux  vegetaux.  P.  125 — 127;  157;  347 — 348. 


Conceptions  of  Assimilation  Reviewed  339 

in  this  descent  the  chemical  energy  which  it  enclosed 
within  it  in  the  potential  state." 

"Every  act  which  gives  out  energy,  which  produces 
heat,  or  movement,  every  manifestation  whatever,  which 
can  be  regarded  as  a  transformation  of  energy,  neces- 
sarily consumes  energy,  and  this  is  borrowed  from  the 
substances  of  the  organism.  The  functioning  muscle 
produces  heat  and  movement,  the  functioning  of  glands 
produces  heat,  the  functioning  of  nerve  and  brain  pro- 
duces a  small  quantity  of  electricity  and  heat.  All  these 
manifestations  of  energy  rest  upon  a  destruction  of 
organic  matter,  a  chemical  simplification  as  the  source 
of  the  energy  manifested.  In  this  way  material  de- 
struction not  only  coincides  with  functional  activity  but 
is  the  measure  and  the  expression  of  it." 

"The  reconstructive  synthesis  of  protoplasm  is  on 
the  contrary  a  phenomenon  of  evident  synthesis,  of  a 
certain  chemical  increase  of  complexity.  Its  formation  at 
the  expense  of  simpler  nutritive  materials  requires  then 
an  appreciable  quantity  of  energy." 

"The  phenomena  of  living  beings,"  continues  this 
author,  "may  be  divided  into  two  categories.  Some  are 
intermittent,  alternative,  and  are  produced  or  accentu- 
ated at  certain  times  but  cannot  be  continuous.  These 
are  functional  processes.  There  are  others  in  which 
this  property  of  sudden  and  intermittent  expenditure  of 
energy  does  not  appear  at  all.  They  are  in  general, 
nutritive  processes.  The  muscle  which  contracts,  func- 
tions. It  has  an  activity  and  a  repose.  During  this  ap- 
parent repose  one  could  not  say  that  it  is  dead.  It  has 
life  and  this  is  here  obscure  in  comparison  with  the 
manifest  activity  of  the  functional  movement." 

"The   phenomena    of    functional   activity   are   those 


34O  Assimilation 

which  catch  the  eye  and  by  which  we  are  inclined  to  char- 
acterize life.  These  are  conditional  on  processes  of 
consumption,  of  chemical  simplification,  of  organic  de- 
struction through  which  energy  is  set  free.  And  it  is 
quite  necessary  that  it  should  be  so,  since  these  functional 
manifestations  expend  energy.  These  phenomena  in 
which  the  vital  activities  are  most  apparent  are  the  least 
specific.  They  have  only  the  character  of  general 
phenomena." 

"The  phenomena  which  accompany  functional  repose 
correspond  to  the  reconstruction  of  the  reserve  materials 
destroyed  in  the  preceding  period,  to  organic  synthesis. 
This  remains  in  the  words  of  Claude  Bernard,  'internal, 
silent,  hidden  in  the  expression  of  its  nature,  reassembling 
silently  the  materials  to  be  expended.  We  never  see  these 
phenomena  of  organization  directly.  Only  the  histolo- 
gist,  the  embryologist  tracing  the  development  of  the 
element  or  of  the  living  being  notes  the  changes,  the 
phases  which  discover  to  him  this  homely  work,  here  a 
deposition  of  material,  there  the  formation  of  a  mem- 
brane or  a  nucleus,  yonder  a  cleavage  or  a  folding,  or  a 
renovation.'  This  category  of  phenomena  is  the  only 
one  which  has  no  direct  analogues.  It  is  peculiar  to  the 
living  being  and  limited  to  it.  This  developmental 
synthesis  is  the  true  vital  phenomenon.  Life  is  a 
creation."  257 

It  is  then  this  reconstructive  synthesis  of  living  matter 
which  goes  on  during  the  so  called  functional  rest  which 
we  must  seek  to  explain  through  the  properties  which  we 
have  postulated  above  for  nervous  energy  taken  as  the 
basis  of  the  vital  phenomenon. 

2B7Dastre:  La  Vie  et  la  Mort.  Paris,  Flammarion,  1902.  P. 
103,  107,  208 — 209,  210 — 211. 


Explanation  of  Assimilation  341 

For  this  purpose  let  us  suppose  in  conformity  with  the 
hypothesis  set  forth  above  that  one  could  construct  an 
elementary  electric  accumulator  capable  of  furnishing  a 
single  given  intensity  or  specificity  of  current  and  that  its 
electro-motive  force  or  difference  of  potential  between  the 
poles  is  proportional  to  the  mass  of  substance  constituting 
its  charge ;  as  if  each  new  increment  however  small  of  this 
mass  constituted  an  element  by  itself  which  would  be 
added  in  serial  order  to  the  others. 

Let  us  consider  two  of  these  accumu- 
lators, A  and  A',  inserted  with  their 
poles  inverted  in  the  same  circuit.  Sup- 
pose  they  are  quite  identical,  except 
that  the  one,  A',  is  entirely  without 
charge,  and  the  other,  A,  has  its  full 
charge.  Let  us  suppose  now  that  the 
current,  c,  generated  by  A  which  tends 
to  charge  A'  can  under  certain  circum- 
stances cause  an  oscillatory  discharge, 
i.  e.,  a  continuous  oscillation  of  the 
current,  now  in  the  direction  of  c,  now 
in  the  contrary  direction  c',  and  that  certain  external  alternating 
currents  could  induce  in  the  oscillating  circuit  sinusoidal  electro- 
motive forces  of  the  same  frequence  as  this  oscillating  discharge 
and  thereby  strengthen  the  sinusoidal  electro-motor  force  of  the 
latter  which  at  the  beginning  was  determined  by  the  original  dif- 
ference in  charge  of  the  two  accumulators  A  and  A'. 

Then  with  each  half  oscillation  the  one  accumulator 
will  become  more  strongly  charged  in  proportion  as  the 
other  discharges,  and  there  will  be  produced  as  a  final 
result  of  the  series  of  oscillations  a  consequent  continual 
increase  of  the  total  mass  of  the  two  accumulators  A  and 
A',  as  long  as  the  saline  solution  serving  as  their  common 
aliment  is  not  insufficient. 

If  the  amount  of  electro-motive  force  contributed  by 
the  induction  current  at  each  oscillation  is  proportional 


342  Assimilation 

to  the  amount  of  electro-motive  force  which  is  directly 
dependent  upon  the  difference  in  charge  between  the  two 
accumulators  existing  at  any  moment,  if  for  example,  it 
represents  a  definite  fraction  of  the  latter,  and  thereby 
will  gradually  decrease  in  amount  as  this  difference  be- 
tween the  two  charges  becomes  less  with  each  oscillation, 
then  both  the  amount  of  this  difference  and  that  of  the 
induced  electro-motive  force  will  sink  to  nothing  after  a 
certain  period  of  time,  theoretically  infinitely  long,  prac- 
tically more  or  less  short,  which  we  can  call  the  period  of 
reconstitution  or  of  replacement  of  material  consumed. 

As  soon  as  the  charges  of  the  two  accumulators  have 
become  equal  there  will  take  place  no  more  provocation 
of  oscillating  currents  and  the  total  mass  of  the  two  ac- 
cumulators whose  increase  had  become  always  smaller 
and  smaller  will  now  not  increase  any  further  at  all. 

But  if  at  this  instant  either  of  the  two  accumulators, 
suddenly  becoming  inserted,  aside  from  its  own  oscillat- 
ing circuit,  into  another  circuit,  discharges  into  the  latter 
wholly  or  partially,  then  the  difference  between  the  re- 
spective charges  of  the  two  accumulators  will  again  be 
present  and  the  former  process  of  oscillation  will  begin 
again.  And  this  will  result  again  in  the  increase  of  the 
total  mass  of  the  two  accumulators  above  the  amount 
which  it  had  already  reached  before  this  last  discharge. 
We  can  compare  this  discharge  of  one  of  the  two  accumu- 
lators outside  the  circuit  of  oscillation  with  the  nervous 
nuclear  discharge  outside  the  nucleus  into  its  surrounding 
protoplasm  or  its  environment  in  general,  that  is  with  the 
biological  functional  excitation  which  produces  the  same 
trophic  effect. 

Further  if  at  the  moment  when  the  two  accumulators 
have  arrived  at  the  condition  of  equality  between  their 


Explanation  of  Assimilations:  The  Vital  Element  343 

respective  charges  and  so  of  repose,  one  of  them  instead 
of  becoming  discharged  into  another  circuit,  becomes  re- 
placed by  a  third  accumulator  whose  charge  is  different 
from  the  other  two  now  equalized  charges,  the  result  will 
be  the  same.  And  the  impulse  given  to  the  process  of 
oscillation  will  be  greater  the  greater  the  difference  be- 
tween the  charge  or  electro-motive  force  of  the  new 
accumulator  and  of  the  old  one  replaced.  In  other  words, 
to  make  use  of  biological  expressions :  the  rejuvenescence 
of  the  specific  potential  elements  formed  by  the  pair  of 
accumulators  will  be  proportionally  greater,  the  more 
quantitatively  unequal  are  the  two  half  elements  which 
have  become  thus  mutually  fecundated. 

If  we  substitute  for  the  conception  of  electro-motive 
force  that  of  nervo-motive  force,  our  hypothesis  concern- 
ing the  nature  of  the  vital  process  in  each  specific  potential 
element  will  consist  simply  in  supposing  that  the  latter  is 
comparable  to  this  pair  of  accumulators  inserted  with  in- 
verted poles  in  the  same  elemental  oscillating  circuit, 
which  we  would  call  intra-nuclear  circuit,  but  in  which 
there  enters  into  play  instead  of  the  alternating  electric 
induction  current,  general  thermal  energy  in  the  same 
way. 

Assimilation,  the  new  formation  of  living  substance, 
would  then  be  dependent,  according  to  the  hypothesis, 
upon  a  kind  of  oscillatory  charging  and  discharging  flux, 
upon  a  kind  of  intra-nuclear  oscillatory  discharge  which 
becomes  provoked  by  the  extra-nuclear  or  functional 
nervous  discharge  in  consequence  of  the  disturbance  of 
the  equilibrium  between  the  nervo-motive  forces  of  the 
two  accumulators  opposite  each  other.  The  vital  element 
would  thus  be  conceived  of  as  only  a  double  specific 


344  Assimilation 

elemental   accumulator  of  nervous  energy   in  continual 
charge  and  discharge. 

As  will  be  noted  we  have  here  a  phenomenon  in  some 
respects  similar  to  the  electric  resonators  of  Hertz,  in 
which  an  electric  discharge  caused  by  the  difference  of 
potential  existing  between  the  two  armatures  of  a  con- 
denser, is  transformed  into  an  oscillatory  discharge.  It 
will  be  appropriate  here  to  indicate  briefly  in  just  what 
this  phenomenon  consists. 

\       TJ    T*  Let  A  and  B  be  the  armatures 

***     •'"*    -*-*  of  a  charged  condenser  which  are 

suddenly  connected  with  each 
other  by  an  external  conductor, 
ArMLB,  in  such  a  way  that  the 
latter  makes  a  circuit  open  only  at 
the  point  D  of  the  di-electric.  In 
the  accompanying  figure  r  repre- 
sents the  total  resistance  of  the 
circuit,  and  L  the  inductance  or  co- 
efficient of  self  induction  of  this 
circuit.  When  the  capacity  c  of 
the  condenser  and  the  inductance 
L  of  the  circuit  are  in  a  certain 
relation  to  each  other,  and  r  is  small,  we  can  get  an  oscillatory  dis- 
charge which  forms  as  it  were  a  sinusoidal  alternating  current ;  that 
is  the  electricity  oscillates  from  A  toward  B  and  from  B  toward  A, 
with  a  frequency  determined  by  the  inductance  L  and  the  capacity 
c.  If  we  cause  the  resistance  r  of  the  circuit  to  become  constantly 
less  by  employing  wires  of  constantly  increasing  thickness,  we 
approach  the  boundary  at  which  this  oscillation  will  be  able  of  itself 
to  continue  indefinitely. 

If  in  this  case,  where  r  is  very  small,  we  excite  in  the 
circuit  by  induction  sinusoidal  alternating  electro-motive 
forces  of  the  same  frequence  as  in  the  oscillatory  dis- 
charge, then  there  will  arise  in  A  and  B  differences  of 
very  many  volts  even  though  the  number  of  volts  so 
induced  is  small. 

Upon  this  principle  depends,  as  is  well  known,  the 


Electric  Resonators  345 

celebrated  experiments  of  Hertz,  which  in  turn  have 
formed  the  point  of  departure  for  wireless  telegraphy. 

It  is  known  also  that  such  an  electric  resonator  has 
been  rightly  compared  to  a  vibrating  dynamic  system,  to 
a  pendulum  which  has  an  oscillation  time  of  its  own,  to  a 
sounding  chord  which  the  smallest  impulses  having  the 
same  frequence  as  itself  can  set  in  vibration,  even  in 
strong  vibration.  What  happens  in  it  is  a  continual 
periodic  transformation  of  energy.  At  the  instant  when 
the  sinusoidal  alternating  current  reaches  its  maximum 
intensity,  one  has  the  maximum  of  actual  energy,  while 
the  condenser,  on  the  other  hand,  possesses  then  no 
potential  energy  whatever.  At  the  instant  when  the  in- 
tensity of  the  current  drops  to  nothing,  the  condenser 
shows  the  greatest  deformation  of  the  respective  di- 
electric, and  possesses  thus  a  potential  energy  fully  equal 
to  the  actual  energy  possessed  by  the  discharge  at  the 
moment  of  its  greatest  intensity,  the  process  being  thus 
exactly  the  same  as  in  a  pendulum  in  which  potential 
energy  is  transformed  continually  into  actual  and  vice 
versa. 

It  will  be  sufficient  here,  for  the  purpose  of  a  remote 
comparison,  to  note  the  fact  just  indicated  that  a  sinu- 
soidal alternating  electro-motive  force  induced  in  such  an 
electric  resonator,  which  need  amount  only  to  a  very  few 
volts,  provided  that  it  be  of  the  same  frequency  as  the 
oscillating  discharge,  will  be  able  to  induce  in  A  and  B 
differences  of  tension  which  may  amount  to  many  volts. 
For  if  we  assume  in  the  current  so  oscillating  the  faculty 
of  depositing  in  each  of  the  armatures  of  the  condenser 
infinitely  small  particles  of  substance  in  series  one  after 
the  other,  so  long  as  the  total  of  their  mass  and  the  con- 
sequent electro-motor  force  does  not  surpass  the  electro- 


346  Assimilation 

motor  force  in  the  opposite  direction,  which  this  current 
possesses  at  this  point  and  at  this  moment,  then  it  will 
not  be  difficult  for  us  to  conceive  of  the  case  in  certain 
respects  analogous,  which  we  have  assumed  for  oscillat- 
ing nervous  discharges,  in  which  the  calorific  oscillations, 
which  replace  here  the  oscillations  of  the  induction  cur- 
rent, continually  increase  the  mass  of  living  substance 
which  will  in  this  way  be  "assimilated." 

Let  us  note  that  in  the  case  of  nervous  currents  we 
must  assume  that  their  specificity  is  constant  even  during 
the  oscillation.  Then  the  duration  of  each  nervous  dis- 
charge, and  hence  of  each  oscillation  also,  in  cases  where 
the  specificity  i  of  the  nervous  current  is  something 
dynamically  equivalent  to  the  intensity  of  the  electric 
current,  will  likewise  be  definite  and  constant  for  every 
given  specificity. 

For  let  us  consider  again  an  electric  current.  If  its 
intensity  i  persists  for  a  time  t,  the  total  actual  energy 
furnished  during  the  whole  of  this  time  by  this  current 
will  be  Eit,  where  E  represents  the  electro-motive  force. 
But  this  total  energy  will  necessarily  be  proportional  to 
the  mass  M  of  the  substance  whose  decomposition  during 
the  time  t  has  produced  this  current;  one  has  thus 
Eit^hm,  where  h  is  a  coefficient  of  proportionality,  de- 
pendent solely  upon  the  units  of  measure  selected.  But 
if  the  supposition  which  we  have  accepted  for  nervous 
currents  in  general  holds  good  also  for  this  electric  cur- 
rent, namely,  that  the  electro-motive  force  is  proportional 
also  to  the  mass  of  substance  which  tends  by  decomposi- 
tion to  produce  the  current,  then  also  E=km,  where  k 
again  is  a  coefficient  of  proportionality  dependent  likewise 
solely  upon  the  units  of  measure  which  are  adopted. 


Source  of  Energy  of  Assimilation  and  Growth  347 

Consequently  the  above  equation  would  take  on  the 
following  form: 

km.  it=hm, 
that  is: 

it=h/k=H, 

where  H  again  is  another  coefficient  of  proportionality 
and  dependent  solely  upon  the  units  of  measure  already 
fixed  above,  and  so  represents  an  arbitrary,  constant 
numerical  value.  It  follows  from  this  that  it  is  constant. 
And  if  i  in  its  turn  is  likewise  constant  for  each  specific 
current,  t  must  also  be  constant;  i.  e.,  to  each  definite 
specificity  of  current,  i,  will  correspond  a  likewise  deter- 
minate and  constant  duration  of  discharge. 

If  then,  no  matter  what  conditions  may  induce  the 
different  discharges  of  a  current  of  the  specificity  i,  all 
these  discharges  can  have  invariably  only  the  same  dura- 
tion t,  and  if  this  holds  also  for  those  which  constitute  the 
oscillating  discharge,  then  the  oscillation  itself,  which 
consists  of  a  double  discharge  of  which  each  one  has  a 
direction  contrary  to  that  of  the  other,  as  we  stated  above, 
will  have  necessarily  a  very  definite  and  constant  period 
of  its  own  which  corresponds  each  time  to  the  particular 
specificity  i  of  its  respective  current. 

It  follows  that  among  all  the  infinite  vibrations  of  the 
different  rays  from  any  calorific  source  whatever,  there 
will  be  certainly  present  also  those  which  have  the  same 
oscillatory  period  as  the  mnemonic  element  in  the  way  of 
reconstituting  itself,  and  those  synchronous  rays  will 
then  be  able  to  give  to  the  oscillating  discharge  of  the 
latter  an  impulse  which  will  be  added  to  that  received 
through  the  difference  in  potential  of  the  pair  of  accumu- 
lators, and  thus  to  have  identically  the  same  effect  as  that 
which  the  sinusoidal-alternating,  electric,  induction  cur- 


348  Assimilation 

rent  has  upon  the  electric  resonator  with  an  equal  period 
of  vibration.  And  this  becomes  so  much  the  more  plaus- 
ible since  Maxwell's  theory,  of  which  it  is  scarcely 
necessary  to  remind  any  one,  and  which  was  wholly 
confirmed  by  the  Hertzian  experiments,  has  demonstrated 
the  essential  identity  of  these  electric,  induction  oscilla- 
tions across  the  di-electric  formed  by  the  air,  with  light 
and  heat  vibrations  in  general.  The  only  difference  con- 
sists in  the  period  of  vibration  which  in  both  the  latter  is 
much  more  rapid  than  in  the  former. 

So  we  can  understand  how  thermal  energy,  whether 
that  which  comes  from  the  irradiation  of  the  sun  and 
from  the  outer  world  in  general,  or  that  which  is  de- 
veloped from  chemical  processes  of  decomposition  and 
oxidation  taking  place  in  the  interior  of  the  organism, 
can,  in  as  far  as  it  is  composed  of  heat  rays  of  the  most 
different  periods  of  oscillation,  constitute  the  general 
external  stimulus  which  activates  indifferently  all  the 
vital  processes  of  synthesis : 

Let  us  note  that  to  each  specific  discharge,  to  the  intra- 
nuclear oscillating  as  well  as  to  the  extra-nuclear  func- 
tional there  will  correspond  very  definite  substances  of 
dissimilation,  for  the  different  specificities  of  the  nervous 
currents  can  be  due  only  to  the  decomposition  of  sub- 
stances likewise  different.  And  even  if  the  diversity  of 
these  extremely  complex  and  unstable  substances  consists 
only  in  the  different  number  and  different  mode  of 
grouping  of  the  same  atoms  of  the  principal  elements 
which  constitute  all  organic  substance,  nevertheless  the 
respective  substances  of  dissimilation  to  which  each  of 
these  complex  substances  will  give  rise,  will  necessarily 
be  different  from  one  another.  These  substances  of  dis- 
similation, definite  and  peculiar  for  each  specific  dis- 


Physico-Chemical  Character  of  Cytoplasm       349 

charge,  will  in  their  turn  afford,  by  their  entire  or  partial 
oxidation,  products  of  excretion  and  secretion  quite 
definite  and  differing  from  one  cell  to  another.  These 
products,  in  their  turn,  thanks  to  their  peculiar  physico- 
chemical  properties,  will  imprint  upon  the  protoplasm  or 
cytoplasm  a  corresponding  physico-chemical  character 
and  a  corresponding  morphological  structure.  So  it  is 
conceivable  how  the  ensemble  of  the  mnemonic  elements 
constituting  a  given  nucleus  can  determine  its  own  proto- 
plasm or  cytoplasm  both  from  the  purely  physico-chemical 
and  from  the  properly  morphological  point  of  view. 

We  arrive  thus  at  a  constant  double  correlation  be- 
tween the  cytoplasm,  the  species  of  nuclear  excitation, 
and  the  substance  of  the  nucleus.  For  the  nuclear  sub- 
stance will  determine  directly  the  specificity  of  the 
corresponding  nervous  current  and  its  rhythm  of  charge 
and  discharge;  and  this  specificity  of  current  thanks  to 
the  substances  of  dissimilation  to  which  it  will  give  rise, 
will  determine  the  respective  cytoplasm.  Conversely,  the 
specificity  of  the  current  or  its  peculiar  rhythm  of  charge 
and  discharge,  once  determined  by  the  functional  stim- 
ulus, will  determine  the  substance  of  synthetization  or 
nuclear  substance,  as  also  the  substances  of  dissimilation 
of  which  the  cytoplasm  is  constituted. 

Let  us  summarize  what  has  been  said.  The  specific 
potential  elements  which  have  presented  themselves  in  the 
preceding  chapter  as  specific  elementary  accumulators, 
and  at  the  beginning  of  this  chapter  as  mnemonic  ele- 
ments, appear  now  as  specific  vital  elements,  that  is  as 
the  smallest  possible  particles  of  organic  substance  cap- 
able of  life.  At  the  same  time  the  denominations 
potential  element,  and  vital  element,  which  might  at  first 
have  appeared  incompatible  with  each  other,  if  the 


350  The  Vital  Element:  Its  Three  Modes 

adjective  potential  had  indicated  a  vital  non-activity  at 
that  time,  become  entirely  compatible  in  consequence  of 
the  hypothesis  which  we  have  just  set  forth.  For  accord- 
ing to  this  hypothesis,  the  element  would  be  potential  in 
so  far  as  each  of  the  two  coupled  accumulators  would  be 
able  to  furnish  at  need  its  proper  extra-nuclear  functional 
nervous  discharge,  and  it  would  at  the  same  time  be  coh- 
ceived  as  in  a  vital  process  by  reason  of  the  intra-nuclear 
oscillating  discharge,  which  continues  incessantly  between 
the  two  accumulators.  Vital  energy  could  thus  present 
itself  in  three  distinct  modes:  (i)  In  the  potential, 
properly  so  called,  which  expresses  itself  in  the  phenom- 
ena of  actual  suspension  of  life  or  lethargy  in  its  widest 
sense;  (2)  In  the  oscillatory  potential  or  the  intra- 
nuclear oscillating  discharge,  which  constitutes  the 
essence  of  the  period  of  so  called  "functional  repose," 
"organic  reconstitution"  of  materials  afterwards  to  be 
consumed,  "assimilative  synthesis,"  or  "vital  creation;" 
(3)  Finally  in  the  actual  proper,  or  the  extra-nuclear 
non-oscillating  discharge,  which  constitutes  the  period  of 
"excitation,"  "functional  activity,"  "wear  and  tear," 
'''consumption  of  material  stored  up  in  the  rest  period," 
"disassimilation,"  or  "vital  destruction." 

As  conclusion  of  our  exposition  let  us  note  very 
briefly  that  also  for  three  others  of  the  most  fundamental 
phenomena  associated  with  vital  activity  this  hypothesis 
upon  the  nature  of  life  presents  at  least  the  beginning  of 
an  explanation.  These  are :  rhythmicity,  a  characteristic 
property  of  all  life  phenomena;  the  phenomena  of  fecun- 
dation and  rejuvenesence  in  general ;  and  nuclear  division 
with  its  characteristic  and  remarkable  details. 

A  whole  series  of  facts  forces  us  to  the  opinion,  that 


Rhythmicity  and  Periodicity  351 

rhythmicity  should  be  reckoned  among  the  most  general 
characteristics  of  the  modes  of  manifestation  of  vital 
energy.  Apart  from  the  fact  that  nearly  all,  and  perhaps 
all  external  physical  stimuli,  from  the  thermal  and 
luminous  to  the  acoustic,  are  characterized  by  vibrations; 
and  the  other  fact,  a  consequence  of  the  first,  of  the 
physiological  action  exercised  by  all  the  rhythmical  or 
periodical  manifestations  of  the  most  diverse  energies, 
we  see  that  a  more  or  less  manifest  and  more  or  less 
regular  periodicity  is  a  fundamental  character  of  all  or 
nearly  all  biological  functions.  One  thinks  at  once,  for 
instance,  of  the  synchronous  rhythm  of  all  the  peristomal 
cilia  of  an  infusorian, — a  rhythm  which  manifests  itself 
in  the  two  parts  of  an  animal  which  has  been  divided, 
provided  these  parts  remain  connected  by  a  bridge  of 
protoplasm ;  of  the  rhythmicity  present  in  the  protozoa  in 
general,  present  even  within  the  cells,  shown  by  the 
pulsation  of  contractile  vacuoles,  which  empty  and  refill 
themselves  continually  at  regular  intervals;  of  the  beat 
of  the  heart,  even  independent  of  its  connection  with  the 
nervous  system;  of  the  similar  pulsations  of  the  whole 
vascular  system,  the  entire  breathing  apparatus,  the 
uterus,  and  of  many  other  organs;  and  finally  of  the 
periodicity  of  a  whole  series  of  physiological  variations, 
which  animals  and  plants  undergo  as  a  result  of  corre- 
sponding variations  of  the  outer  world,  but  which  persist 
unaltered  for  some  time  even  when  the  outer  world,  or 
the  periodicity  of  its  variations,  may  have  changed. 

Now  it  is  not  difficult  to  conceive  of  this  rhythmicity 
or  periodicity  which  nearly  all  biological  functions  pre- 
sent, as  a  consequence  more  or  less  direct  or  indirect  of 
the  vital  phenomenon  in  all  its  generality,  when  this 


352  Fecundation 

phenomenon,  be  it  only  in  so  far  as  a  phenomenon  of 
assimilation,  i*  itself  essentially  a  rhythmic  phenomenon. 

In  regard  to  fecundation  we  know  that  it  was  Spencer 
who  first  recognized  what  has  been  more  or  less  explicitly 
accepted  by  others,  that  it  consisted  probably  in  a  per- 
turbation of  an  equilibrium  which  tended  toward  a 
stability  unfavorable  to  vital  activity.258 

Now  we  have  already  seen  how  our  hypothesis  set 
forth  above  is  able  to  make  at  once  conceivable  in  what 
this  equilibrium  unfavorable  to  vital  activity  may  consist. 
According  to  this  hypothesis,  it  would  consist  in  the 
equalization  toward  which  the  masses,  and  the  corres- 
ponding potentials,  of  the  coupled  accumulators  of  each 
mnemonic  element  would  tend,  and  which  they  would 
eventually  attain,  and  this  equilibrium  would  be  disturbed 
by  the  substitution  for  one  of  these  accumulators  of  an- 
other specifically  equal  to  it  but  differing  in  mass  and 
potential.  And  it  is  precisely  in  this  function  of  fecunda- 
tion, of  replacing  in  each  couple  one  of  the  specific 
accumulators  by  another  differing  quantitatively  as 
widely  as  possible,  that  we  find  an  explanation  of  the  fact 
that  the  rejuvenation  of  the  germ  and  the  consequent 
vitality  of  the  progeny  to  which  fecundation  tends,  are 
proportionally  greater  when  fecundation  occurs  not  be- 
tween individuals  too  closely  related  but  rather  between 
individuals  which  belong  indeed  to  the  same  species  but 
are  somewhat  dissimilar. 

According  to  the  same  hypothesis,  this  equilibrium 
could  also  be  deranged  by  the  extra-nuclear  discharge  of 
one  of  the  two  coupled  accumulators,  and  this  is  just  what 

258Spencer:  Principles  of  Biology.  I,  P.  340—341,  and  II.  P. 
614—616. 


Fecundation  353 

is  demonstrated  by  the  universally  known  experiments 
upon  the  rejuvenescence  of  the  infusoria,  by  which  it 
appears  that  this  rejuvenescence  can  be  re-acquired  even 
without  any  need  of  the  ordinary  fecundating  conjuga- 
tion, simply  by  causing  some  change  in  the  surrounding 
conditions  of  life,  and  thereby  provoking  a  strong  renewal 
of  the  functional  activity  of  the  animal.259 

Let  us  note  parenthetically  that  if  oscillating  dis- 
charges take  place  between  the  corresponding  separated 
specific  accumulators  or  half  mnemonic  elements  of  the 
egg  and  spermatozoon  respectively  even  when  the  egg 
and  the  spermatozoon  are  still  relatively  distant  from 
each  other,  i.  e.  before  they  could  coalesce  into  a  single 
fecundated  nucleus,  we  can  then  understand  how  the 
space  between  each  pair  of  these  elements  can  and  must 
function  just  as  the  deformed  di-electric  between  the  two 
armatures  of  the  condenser  of  an  electric  resonator,  and 
thus  be  constrained  to  produce  the  attraction  of  each 
spermatic  half  element  to  the  corresponding  half  element 
of  the  egg.  And  this  would  have  as  a  final  result  an 
energetic  reciprocal  attraction  between  the  egg  and  the 
spermatozoon. 

The  real  cause  of  the  sexual  attraction  of  the  two 
germs,  male  and  female,  would  then  reside  in  their  capac- 
ity of  vibrating  in  unison.  Conversely  the  absence  of  all 
attraction  between  ovum  and  spermatozoon  belonging  to 
animal  or  vegetable  species  too  different  in  kind  would 
be  due  to  the  fact  that  the  one  germ  is  constituted  by 
potential  half  elements  of  which  too  many  are  specifically 

2B9Compare  e.  g.  Hartog:  Problems  of  Reproduction:  Conju- 
gation, Fertilisation  and  Rejuvenescence.  The  Contemporary  Re- 
view, July  1892;  esp.  P.  94 — 95,  100 — 102. 


354  Karyokinesis 

completely  different  from  those  of  the  other  germ,  and 
consequently  they  are  incapable  of  vibrating  together 
with  the  same  rhythmicity. 

Finally  as  to  indirect  or  karyokinetic  cell  division,  let 
us  admit  that,  when  each  of  the  two  coupled  accumu- 
lators, in  consequence  of  the  continual  increase  of  its 
mass  attains  too  high  a  potential,  the  two  halves  of  each 
of  these  accumulators  will  tend  to  repel  each  other,  just  as 
would  for  example,  the  two  halves  of  a  conducting  sphere 
or  disc,  charged  with  too  great  a  quantity  of  static 
electiicity  of  the  same  sign. 

If  we  admit  at  the  same  time,  that  the  separation  of 
the  two  halves  of  each  accumulator  would  break  the  cir- 
cuit of  oscillation,  as  would  seem  indicated  by  the  rupture, 
retraction,  and  disappearance  of  the  meshes  of  the  nuclear 
reticulum  during  mitosis,  and  thus  suspend  abruptly  the 
oscillating  discharge,  then  the  actual  energy  of  this  dis- 
charge still  in  activity  at  that  moment  will  become  trans- 
formed into  potential  energy,  and  discharge  itself  upon 
the  first  little  bit  of  substance,  or  centrosome,  most 
capable  of  receiving  it.  Consequently,  without  pretending 
thus  to  be  able  to  penetrate  into  the  smallest  details  of 
this  phenomenon,  we  understand  nevertheless  how  the 
vital  phenomena  of  dynamic  order,  which  are  due  to  the 
oscillating  nervous  discharge,  must  then  necessarily  be 
followed  by  phenomena  of  static  order,  like  those  which 
are  characteristic  of  the  karyokinetic  cell  division. 

We  limit  ourselves  here  to  recalling  only : 

i.  Delage's  observation  that  in  indirect  division  the 
longitudinal  splitting  of  the  chromosomes  or  of  the 
nuclear  filament  begins  before  achromatic  filaments  are 
present  which  are  capable  of  exerting  upon  them  any  pull 


Karyo  kinesis  355 

whatever,  which  warrants  the  inference  that  it  is  repul- 
sion which  operates  between  the  two  halves.260 

2.  Hanseman's     observation,     that     during    karyo- 
kinesis    all    the    peculiarly   vital    functions    of    the    cell, 
as    assimilation,    secretion,    etc.,    etc.,    are    completely 
suspended.261 

3.  Watase's   observation,    according   to   which   the 
centrosome  in  reality  is  only  a  simple  cytomicrosome  but 
of  greater  circumference  and  greater  force  of  attraction, 
and  that  the  cytomicrosomes  which  always  lie  at  the  meet- 
ing point  of  three  or  more  cytoplasmic  fibers  likewise  are 
nothing  else  than  small  temporary  clumps  quite  aspecific 
which  form  anew  in  each  cell  division  from  the  contract- 
ing substance  of  the  cytoplasmic  fibers  themselves.262 

4.  Ziegler's  experiment,  in  which  the  poles  of  the 
horseshoe  magnet  took  the  place  of  centrosomes  and  acted 
upon  iron  dust  strewn  upon  a  thin  horizontal  wax  plate 
upon   which   previously   pieces  of   iron   wire  of   forms 
similar  to  that  of  the  chromosomes  had  been  placed,  and 
in  which  figures  were  obtained  which  were  similar  to 
those  presented   in   nuclear  division,   which  is   a  direct 
proof  of  the  conception  already  advanced  by  Roux,  that 
in  the  attraction  exerted  by  the  centrosomes  upon  the 
chromosomes  there  are  in  play  static  energies  of  nature 
similar  to  that  of  magnetic  force  or  of  static  electricity.263 

200Delage:    L'heredite  etc.     P.  149— 150. 

261Hansemann :  Studien  iiber  die  Spezifizitat,  den  Altruismus 
und  die  Anaplasie  der  Zellen.  P.  10. 

2<52Watase:  On  the  nature  of  Cell-organisation.  Biol.  Lect.  at 
the  Mar.  Biol.  Lab.  of  Wood's  Holl,  Summer  Session,  1893.  Bos- 
ton, U.  S.  A.,  Ginn,  1894.  P-  92 — 93  5  und  Origin  of  the  Centrosomes, 
Ibid.  Summer  Session  1894;  Ginn,  1896.  P.  282,  285. 

2a3Ziegler:  Untersuchungen  iiber  die  Zellteilung,  Verhandl.  der 
Deutschen  Zoolog.  Gesellsch.,  Leipzig  1895.  P.  78 — 83.  —  Roux: 


356  Conclusion 

Conclusion 

As  the  reader  who  has  followed  us  thus  far  has  al- 
ready noted,  there  are  three  new  hypotheses  or  three  new 
fundamental  conceptions  which  we  submit  to  the  judg- 
ment of  biologists  and  of  positive  philosophers  in  general. 
Although  they  support  one  another  mutually  and  all  rest 
upon  the  same  general  idea  of  the  vital  phenomenon,  they 
are,  nevertheless,  independent  of  one  another,  especially 
the  first  two  are  independent  of  the  third. 

The  first  is  the  hypothesis  of  centro-epigenesis  to 
which  we,  as  was  said  in  the  preface  and  explained  in  the 
first  chapter,  were  led  by  the  fundamental  biogenetic  law 
of  the  repetition  of  phylogeny  by  ontogeny  with  all  its 
more  or  less  mediate  or  immediate  results. 

The  second  hypothesis  is  that  according  to  which  each 
specific  nervous  current  deposits  a  very  definite  substance 
which,  in  its  turn,  is  capable  of  provoking  again  exclu- 
sively the  same  specificity  of  current  as  that  by  which  it 
was  itself  deposited.  This  idea  has  enabled  us  on  the  one 
hand  with  the  aid  of  the  centro-epigenetic  hypothesis  to 
explain  directly  the  inheritance  of  acquired  characters; 
and  has  on  the  other  hand  by  itself  alone  afforded  the 
immediate  explanation  of  all  the  mnemonic  phenomena  in 
the  widest  sense  of  the  word,  from  histologic  specializa- 
tion, in  consequence  of  which  the  cells  answer  always 
only  in  the  same  accustomed  way  to  the  most  different 
accidental  stimuli,  up  to  the  psycho-mnemonic  phenom- 
ena or  phenomena  of  memory  properly  so  called. 

"Dber  die  Bedeutung  der  Kernteilungsfiguren,  Leipzig,  Engelmann, 
1883,  P.  18,  Gesamm.  Abhandl.  Bd.  II,  P.  142.  —  Marcus  Hartog: 
The  Dual  Force  of  the  Dividing  Cell,  Part  I :  The  Achromatic  Spin- 
dle Figure  illustrated  by  Magnetic  Chains  of  Force,  from  the  Pro- 
ceedings of  the  Royal  Society,  B,  Vol.  76,  1905,  especially  P.  555—559- 


Conclusion  357 

The  third  hypothesis  attributes  the  vital  phenomenon 
essentially  to  an  intra-nuclear  oscillating  nervous  dis- 
charge ;  and  this  idea  has  enabled  us,  with  the  help  of  the 
above  mentioned  second  hypothesis  of  specific  accumu- 
lators, to  explain  likewise  the  fundamental  property  of 
the  life  phenomenon,  which  consists  in  assimilation. 

It  is  hardly  necessary  to  state  that  the  first  and  second 
hypotheses  although,  as  we  'have  said,  all  the  three 
hypotheses  support  each  other  mutually,  are  yet  totally 
independent  of  the  third,  and  therefore  can  stand  equally 
well  whether  the  latter  is  accepted  or  rejected. 

We  do  not  venture  to  offer  this  latter  as  a  true  and 
proper  hypothesis.  The  phenomenon  of  life  is  still  too 
little  established  for  so  bold  a  venture.  We  consider  it 
only  as  a  provisional  scheme  of  the  vital  process  which 
may  serve  as  an  initial  concrete  basis  for  further  investi- 
gation into  the  nature  of  life.  For  in  affording 
provisionally  any  firm  foundation  upon  which  the  discus- 
sion of  a  question  still  awaiting  solution  can  be  based,  one 
attains  always  the  great  advantage  of  determining  exactly 
the  conditions  of  the  question,  of  showing  clearly  the 
untenability  of  certain  views  which  was  not  possible 
formerly  while  the  question  had  yet  too  indefinite  a  form, 
and  of  bringing  us  in  this  way  slowly  but  certainly  nearer 
to  a  correct  understanding  of  the  phenomenon,  in  propor- 
tion as  after  discarding  the  untenable  propositions  the 
tenable  stand  out  more  clearly  and  convincingly  and 
thereby  are  given  a  more  firm  foundation. 

It  remains  then  only  to  await  quietly  the  judgment  of 
the  critic  and  to  express  in  advance  our  thanks  to  all 
those  who  are  willing  to  accord  us  friendly  support  in 
word  and  deed,  and  thereby  make  possible  a  somewhat 
more  thorough  elaboration  of  the  subject  which  we  were 


358  Conclusion 

able  here  to  handle  only  too  cursorily.  We  should  be 
especially  grateful  to  those  who  along  with  their  crit- 
icisms and  objections  would  be  good  enough  to  send  us 
word  of  any  new  facts  which  can  be  adduced  either  in 
support  of  any  of  our  three  hypotheses,  or  in  opposition 
to  them. 


APPENDIX 


ON  THE  MNEMONIC  ORIGIN  AND  NATURE  OF 
AFFECTIVE  TENDENCIES.1 

If  we  observe  the  behavior  of  the  various  organisms 
from  the  unicellular  up  to  man,  we  see  that  a  large  num- 
ber of  their  processes,  and  especially  the  most  important 
ones,  may  be  regarded  as  manifestations  of  a  tendency 
of  the  organism  to  maintain  or  to  restore  its  "stationary" 
physiological  state  (to  use  the  term  of  Ostwald's  ener- 
getics). 

In  other  words,  if  we  call  "affective"  that  particular 
class  of  organic  tendencies  which  appear  subjectively  in 
man  as  "desires"  or  "appetites"  or  "needs"  and  objec- 
tively in  both  man  and  animals  as  "movements"  com- 
pleted or  incipient  (except  those  that  have  become 
mechanical  in  character),  then  a  large  number  of  the 
principal  "affective  tendencies"  thus  defined  may  be  at 
once  reduced  to  the  single  fundamental  tendency  of  each 
organism  to  preserve  its  "physiological  invariability." 

For  instance,  we  see  that  hunger,  the  most  fundamen- 
tal of  all  affective  tendencies,  is  in  reality  nothing  but 
the  tendency  to  keep,  or  restore  that  qualitative  and 
quantitative  condition  of  the  nutritive  system  of  the  body 
which  will  make  possible  a  continuation  of  the  stationary 

translated  for  The  Monist  (July,  1911)  by  L.  G.  Robinson 
from  Rivista  di  Scienza  Vol.  XI,  3,  1909. 

361  ' 


362  Appendix 

metabolic  state.  This  tendency  of  an  organism  toward 
the  invariability  of  its  own  metabolism  has  become,  in 
the  course  of  its  phyletic  evolution,  an  inherent  tendency 
to  pass  through  all  the  transient  physiological  states  that 
could  re-establish  this  necessary  condition  within  it,  hence, 
a  tendency  to  perform  all  movements  that  have  nour- 
ishment for  their  object;  yet  in  doing  this  it  has  never 
relinquished  its  original  character.  This  results  directly 
from  the  fact  that  all  inclination  to  procure  new  food 
ceases  as  soon  as  the  internal  nutritive  system  of  the 
animal  has  attained  its  normal  state. 

Accordingly,  the  hydra  or  sea  anemone  does  not  react 
positively  to  food  except  when  its  metabolism  is  in  a 
state  requiring  more  nutriment,  "unless,"  says  Jennings, 
"metabolism  is  in  such  a  state  as  to  require  more  ma- 
terial"; for  instance,  when  the  large  sea  anemone 
Stoichactis  helianthus  is  not  hungry,  a  bit  of  food 
placed  upon  its  oral  disk  occasions  the  same  character- 
istic "rejecting  reaction"  as  if  it  were  any  other  disturb- 
ing object.  And  all  other  organisms,  the  higher  as  well 
as  the  lower,  behave  in  exactly  the  same  fashion.2 

SchifFs  experiments  of  injecting  nutritive  substances 
into  the  veins  of  dogs  are  direct  evidence,  on  the  other 
hand,  that  the  fundamental  condition  of  hunger  is  the  ab- 
sence of  histogenetic  substances  in  the  blood,  for  these 
injections  resulted  not  only  in  nourishing  the  animal  but 
also  in  allaying  its  hunger. 

Moreover  the  fact  that  hunger,  especially  as  long 
as  it  is  only  moderate,  assumes  in  man  the  form  of  a 
special  and  localized  sensation  originating  in  the  wall  of 
the  stomach  and  being  the  sole  cause  of  the  activities 

2H.  S.  Jennings,  Behavior  of  Lozver  Organisms,  pp.  202,  205, 
etc.  New  York,  MacMillan,  1906. 


Affective  Tendencies  363 

induced  by  real  hunger,  is — it  is  scarcely  necessary  to 
state — a  natural  consequence  and  of  but  secondary  im- 
portance. It  is  only  one  of  many  forms  in  which  we  see 
the  substitution  of  the  part  for  the  whole,  and  this  phe- 
nomenon characteristic  of  all  mnemonic  physiological 
processes  appears  also  in  the  tendency  to  physiological 
invariability,  which  is  also  essentially  mnemonic  as  we 
shall  see  more  clearly  later  on.  These  peculiar  sensa- 
tions localized  in  the  gastric  mucous  membrane  and 
produced  by  its  swelling  or  by  some  other  more  or  less 
similar  change  caused  by  the  empty  condition  of  the 
stomach,  usually  take  place  before  or  simultaneously 
with  the  actual  lack  of  histogenetic  substance  in  the  blood, 
and  so  finally  became  representative  or  vicarious  signs  of 
hunger. 

The  same  is  true  of  thirst  and  of  its  localization  in 
the  upper  part  of  the  alimentary  canal. 

We  might  pass  on  from  hunger  and  thirst  to  the 
other  more  or  less  fundamental  organic  "appetites"  or 
"needs."  All  would  show  us  in  their  different  manifes- 
tations that  they  are  directed  simply  and  solely  toward 
the  restoration  of  the  stationary  physiological  state, 
which  has  been  lost  or  in  some  way  disturbed. 

Thus  there  exists  for  every  animal  species  an  opti- 
mum of  environment  with  reference  to  the  degree  of 
saturation  of  the  solution  in  which  the  animal  lives,  to 
the  temperature  or  to  the  intensity  of  light,  etc.,  above 
and  below  which  the  organism  cannot  maintain  its  nor- 
mal physiological  state  and  which  the  animal  makes 
every  effort  to  maintain. 

So  for  instance  we  see  that  the  infusorian  Paramac- 
cium  at  28°  C.  reacts  negatively  toward  a  rising  but  not 
toward  a  falling  temperature,  whereas  at  22°  C.  it 


364  Appendix 

reacts  negatively  toward  a  falling  but  not  toward  a  rising 
temperature.  We  see  also  that  Euglena  in  a  moderate 
light  reacts  negatively  toward  a  decrease  but  not  toward 
an  increase  in  the  intensity  of  light,  whereas  in  a  stronger 
light  the  reaction  is  exactly  reversed.3 

The  tendency  of  organisms  to  maintain  their  physio- 
logical state  unaltered  consequently  resolves  itself  into  a 
tendency  to  invariability  in  their  external  and  internal 
environments.  Thus  for  instance,  oysters  and  actinians 
close  when  exposed  to  the  air;  that  is,  they  behave  so  as 
to  keep  the  standard  of  moisture  unaltered  within  them- 
selves and  in  their  immediate  surroundings.4 

To  the  tendency  toward  invariability  of  environment 
is  due  also  the  position  which  the  organism  takes  with 
relation  to  the  direction  of  the  various  forces  to  which 
it  is  exposed,  especially  gravity.  Hence  the  tendency  to 
preserve  or  restore  its  normal  position.  Thus,  for  in- 
stance, the  amoeba  draws  in  its  pseudopodia  when  they 
come  in  contact  with  solid  non-edible  bodies;  but  if  it  is 
lifted  off  the  bottom  of  the  aquarium  and  is  suspended 
in  the  water  it  stretches  out  its  pseudopodia  in  all  direc- 
tions. As  soon  as  one  of  these  touches  a  solid  object, 
the  amoeba  takes  hold  of  it,  draws  its  body  over  to  it,  and 
again  resumes  its  original  position.  Likewise  a  starfish 
when  inverted  tries  to  turn,  over,  that  is,  to  return  to 
its  normal  environmental  conditions  with  relation  to 
gravity.5 

All  "needs"to  throw  off  substances  which  have  been 
produced  by  the  general  metabolism  and  which  the  or- 

3Jennings,  Behavior  of  Lower  Organisms,  pp.  294-295. 

4H.  Pieron,  Uevolution  de  la  memoire,  pp.  29,  74.  Paris,  Flam- 
marion,  1910. 

5K.  C.  Schneider,  Vorlesungen  iiber  Tier  psychologic,  pp.  5,  57. 
Leipsic,  Engelmann,  1909. 


Affective  Tendencies  365 

ganism  can  no  longer  use,  are  likewise  no  exceptions  to 
this  general  rule.  For,  although  the  need  for  eliminat- 
ing them  may  be  called  forth  by  certain  vicarious  local 
sensations  capable  of  evoking  the  act  of  expulsion  in  ad- 
vance, yet  in  reality,  whether  in  the  case  of  the  smallest 
and  simplest  infusorians  or  of  the  most  highly  developed 
vertebrates,  it  is  due  only  to  the  circumstance  that  the 
accumulation  of  this  waste  material  within  the  organism 
would  eventually  disturb  its  normal  physiological  state. 

To  this  class  of  eliminative  affective  tendencies  'the 
sexual  hunger  seems  to  belong.  For  we  know  that  cer- 
tain recent  theories  are  inclined  to  regard  the  whole  or- 
ganism rather  than  any  one  definite  part  of  the  body  as 
the  seat  of  sexual  hunger  just  as  in  the  case  of  hunger 
proper,  and  at  the  same  time  to  regard  it  as  due  to  the 
need  of  eliminating  the  germinal  substance.6 

It  may  be  that  just  as  infusoria  after  a  certain  num- 
ber of  divisions  become  subject  to  "senescence"  (Maupas) 
so  also  the  germinal  substance  constantly  produced  in  the 
adult  organism,  especially  after  it  has  undergone  the  re- 
ducing divisions,  may  be  subject  to  a  similar  degenera- 
tion if  it  has  not  also  experienced  the  requisite  caryo- 
gamic  rejuvenation.  Therefore  it  seems  quite  plausible 
that  "sexual  hunger"  is  originally  nothing  but  the  ten- 
dency of  the  organism  to  free  itself  of  this  "senile  cor- 
ruption" which  the  germinal  substance,  being  in  its 
nature  a  nuclear  substance  awaiting  fertilization,  pro- 
duces by  means  of  its  hormonic  secretions  or  substances 
of  disintegration  and  spreads  throughout  the  entire  or- 
ganism. 

°See,  for  instance,  though  only  in  certain  respects,  J.  Roux, 
L'instinct  d'amour,  ch.  I,  "Base  organique  de  1'instinct  sexuel." 
Paris,  Bailliere,  1904. 


366  Appendix 

The  more  or  less  brilliant  or  striking  "wedding  gar- 
ment" which  nearly  all  animals  assume  when  in  love, 
arises  from  an  abnormal  condition  of  general  hyper- 
secretion  occasioned  again  by  the  hormonic  products  of 
the  germinal  substance.  At  any  rate  it  shows  how  deep 
is  the  physiological  disturbance  caused  in  all  somatic 
cells  by  the  germinal  substance.  The  effort  to  expel  so 
disturbing  an  element  then  becomes  a  tendency  to  copu- 
lation as  means  of  effecting  this  expulsion.  Hence  the 
fundamentally  selfish  character  (nature  fonder ement 
ego'iste)  of  sexual  love  which  Ribot  rightly  emphasizes: 
"In  the  immense  majority  of  animals,  and  frequently 
in  man,  the  sexual  instinct  is  not  accompanied  by  any 
tender  emotion.  The  act  once  accomplished,  there  is 
separation  and  forgetting."  7 

It  remains  to  be  explained  why  copulation  of  the 
sexes  is  the  only  means  of  eliminating  the  germinal 
substance,  whereas  the  single  individual  is  sufficient  for 
the  removal  of  all  other  more  or  less  similar  waste 
matter. 

It  is  easy  to  suppose  that  the  reason  lies  in  the 
peculiar  nature  of  the  substance  itself,  and  there  are  two 
circumstances  that  may  perhaps,  if  considered  together, 
contribute  a  little  to  the  desired  explanation:  First,  the 
attraction  by  the  ovum  of  the  spermatozoon  even  at  some 
distance  by  means  of  secretions  diffused  in  all  direc- 
tions; and  second,  the  fact  that  hermaphroditism  prob- 
ably preceded  sexual  dimorphism  in  the  phylogeny  of 
pluricellular  organisms.  Still  we  must  recognize  the  fact 
that  the  phylogenetic  process,  which  by  this  elimina- 

7Th.  Ribot,  La  psychologic  des  sentiments,  p.  258.  Paris,  Alcan, 
1908  (English  translation  in  Contemporary  Science  Series,  London, 
1911,  p.  253).— Essai  sur  les  passions,  pp.  67  ff.  Paris,  Alcan,  1907. 


Affective  Tendencies  367 

tion  has  become  so  closely  associated  with  copulation, 
is  still  far  from  a  satisfactory  explanation. 

But  even  in  this  incomplete  form  the  hypothesis 
which  attributes  to  the  sexual  instinct  no  further  signifi- 
cance than  a  tendency  to  eliminate  a  disturbing  element, 
permits  us  to  present  this  instinct  in  very  different 
light  from  that  in  which  it  has  hitherto  appeared. 
For  were  this  hypothesis  to  be  accepted,  the  sexual  in- 
stinct would  not  have  'originated  and  developed  for  the 
"good"  of  the  species,  but  of  the  individual.  It  would 
therefore  not  represent  the  "will  of  the  species"  im- 
posing itself  upon  the  individual,  as  most  people  now 
maintain  with  '  Schopenhauer,  but  much  rather  would  it 
mean  here  as  always  the  "will"  of  the  single  individual; 
that  is,  the  usual  tendency  to  keep  its  stationary  physio- 
logical condition  unchanged.  And  instead  of  seeing  in 
it  with  Weismann  and  all  neo-Darwinists  a  new  evidence 
of  the  alleged  omnipotence  of  natural  selection,  La- 
marck's principle  of  individual  adaptation  combined  with 
the  inheritance  of  acquired  characters  would  be  sufficient 
to  account  for  this  as  well  as  for  all  other  instincts. 

Moreover,  the  "elimination"  hypothesis  is  sufficient 
by  itself  to  explain  certain  peculiarities  of  this  impulse 
which  would  be  quite  incomprehensible  from  the  stand- 
point of  Schopenhauer  and 'the  neo-Darwinians. 

Ribot,  for  instance,  is  surprised  that  an  instinct 
which  is  so  exceedingly  important  for  the  continuance 
of  the  species  is  so  often  subjected  to  certain  perversions 
which  seem  to  involve  its  complete  negation.8 

The  fact  that  such  perversions  are  common  accords 
poorly  with  the  hypothesis  that  the  only  reason  for  the 

8Ribot,  La  psych,  des  Sent.,  pp.  263,  265  (Engl.  ed.,  pp.  257,  259). 


368  Appendix 

existence  of  such  an  instinct  is  the  need  for  the  con- 
tiriuance  of  the  race. 

Finally,  the  fact  that  both  animals  and  man  now 
desire  copulation  or  even  certain  secondary  sexual  rela- 
tions for  their  own  sakes — hence  independently  of  the 
act  of  the  elimination  of  the  germinal  substance,  perhaps 
even  in  default  of  any  to  eliminate, — this  also,  as  we 
shall  better  appreciate  later  on,  is  only  the  consequence 
of  the  mnemonic  law  already  mentioned  of  the  substi- 
tution of  the  part  for  the  whole,  and  of  its  derivative, 
the  law  of  the  transference  of  affective  tendencies.  Ac- 
cording to  this  law  all  phenomena  that  constantly  ac- 
company the  satisfaction  of  certain  affectivities  become 
also  in  their  turn  objects  of  desire,  and  all  habits  ac- 
quired for  the  satisfaction  or  in  the  satisfaction  of  cer- 
tain affectivities  likewise  become  affective  tendencies. 

If  the  sexual  instinct  also,  on  account  of  its  origin, 
can  be  referred  to  the  class  of  tendencies  which  serve  to 
maintain  the  stationary  physiological  condition  of  the 
organism,  then  the  above  law  is  open  to  no  exception 
as  far  as  the  fundamental  organic  tendencies  are  con- 
cerned. Hence  we  can  sum  it  up  in  the  following 
words : 

Every  organism  is  a  physiological  system  in  a  sta- 
tionary condition  and  tends  to  preserve  this  condition  or 
to  restore  it  as  soon  as  it  is  disturbed  by  any  variation 
occurring  within  or  without  the  organism.  This  prop- 
erty constitutes  the  foundation  and  essence  of  all 
"needs,"  of  all  "desires,"  of  all  the  most  important 
organic  "appetites."  All  movements  of  approach  or 
withdrawal,  of  attack  of  fight,  of  taking  or  rejecting, 
which  animals  make  are  only  so  many  direct  or  in- 
direct consequences  of  this  perfectly  general  tendency 


Affective  Tendencies  369 

of  every  stationary  physiological  condition  to  remain 
constant.  We  shall  soon  see  that  this  tendency  in  its 
turn  is  only  the  direct  result  of  the  mnemonic  faculty 
characteristic  of  all  living  matter. 

This  single  physiological  tendency  of  a  general  kind, 
accordingly,  is  sufficient  to  give  rise  to  a  large  number 
of  the  most  diversified  particular  affective  tendencies. 
Thus  every  cause  of  disturbance  will  produce  a  corres- 
ponding tendency  to  repulsion  with  special  characteris- 
tics determined  by  the  kind  of  disturbance,  by  its 
strength,  and  by  the  modes  of  reaction  tending  to  circum- 
vent the  disturbing  factor ;  and  for  every  incidental  means 
of  preserving  or  restoring  the  normal  physiological  con- 
dition, there  will  be  a  quite  definite  corresponding  ten- 
dency such  as  "longing,"  "desire,"  "attraction"  and  so 
forth. 

Even  the  instinct  of  self-preservation — when  under- 
stood in  the  usual  narrow  sense  of  "preservation  of 
one's  own  life" — is  only  a  particular  derivative  and 
direct  consequence  of  this  very  general  tendency  to  pre- 
serve physiological  invariability.  For  every  condition 
which  would  eventually  lead  to  death  first  presents  itself 
as  a  mere  disturbance,  and  it  is  only  as  such  that  the 
animal  tries  and  learns  to  avoid  it.  Jenning's  amoeba, 
for  instance,  which  had  been  completely  swallowed  by 
another  amoeba,  but  had  succeeded  in  getting  away,  did 
not  in  all  probability  flee  from  a  phenomenon  that  en- 
dangered its  life,  but  from  a  condition  in  its  environ- 
ment which  even  though  a  profound  disturbance,  was 
nevertheless  nothing  but  a  disturbance. 

It  is  well  known  that  Quinton  was  the  first  to  de- 
velop a  theory  that  organisms  tend  to  maintain  in  their 
internal  intercellular  environment  the  same  chemical 


370  Appendi.v 

and  physical  conditions  that  obtained  in  the  primordial 
environment  when  life  first  appeared  on  earth.9 

But  it  is  easily  seen  that  our  theory  is  limited  to  a 
consideration  of  the  tendency  to  invariability  only  so  far 
as  it  manifests  itself  each  moment  in  the  behavior  of 
each  individual.  Therefore  instead  of  serving  as  a 
far  too  one-sided  starting  point  for  the  explanation  of 
the  evolution  of  species  it  forms  the  basis  upon  which 
all  the  most  important  affective  tendencies  of  the  animal 
world  may  be  built  up. 

As  a  factor  of  invariability  for  the  individual,  this 
tendency  to  preserve  its  stationary  physiological  condi- 
tion is  indeed  one  of  the  most  important  factors  in  the 
variation  and  progress  of  the  species,  but  in  quite  a 
different  way  from  that  pointed  out  by  Quinton.  For 
from  this  tendency  arose  and  developed  the  power  of 
motion  which  is  the  greatest  difference  between  plants 
and  animals,  and  with  which  also  has  kept  pace  the 
development  and  perfection  of  the  whole  motor  ap- 
paratus, including  that  of  the  nerves  and  senses,  which 
plays  so  important  a  part  in  determining  the  character- 
istics which  distinguish  the  different  zoological  species. 
Finally  as  a  factor  of  individual  invariability  it  has 
proved  by  its  effect  on  man  to  be  one  of  the  most  con- 
spicuous factors  in  all  social  evolution,  for  we  may 
well  say  that  technical  inventions  and  industrial  products 
from  the  first  cave  dwellings,  the  first  skins  used  for 
clothing,  the  first  discovery  of  fire  to  the  most  complex 
attainments  of  to-day  have  tended  constantly  more  or 
less  directly  or  indirectly  towards  one  single  goal, 

9R.  Quinton,  L'eau  de  wier,  milieu  organique.  Especially  Book 
II,  "Loi  generate  de  Constance  originelle,"  pp.  429-456.  Paris,  Mas- 
son,  1904. 


Affective  Tendencies  371 


namely  the  artificial  maintenance  of  the  greatest  possi- 
ble constancy  in  the  environment,  which  is  the  necessary 
and  sufficient  condition  for  preserving  physiological 
invariability. 

n. 

Closely  connected  with  this  inherent  fundamental 
tendency  of  every  organism  to  strive  to  preserve  its  nor- 
mal physiological  condition  or  to  restore  it  as  soon  as  it 
is  disturbed,  is  still  another  attribute  which  in  its  turn 
becomes  the  source  of  new  affectivities. 

For  as  soon  as  the  previous  stationary  condition  can- 
not be  restored  by  any  means,  that  is  by  any  movements 
or  change  of  location,  the  organism  disposes  itself  in  a 
new  stationary  condition  consistent  with  its  new  external 
and  internal  environment.  In  this  way  there  originate 
a  large  number  of  new  phenomena  called  "adaptations." 
Thus,  for  instance,  Dallinger's  classical  experiments 
on  the  acclimatization  of  lower  organisms — suggested  by 
the  observation  that  many  organisms  usually  living  in 
water  of  an  ordinary  temperature,  also  live  and  flourish 
in  the  hottest  spring, — have  proved  that  Infusoria  may 
gradually  become  accustomed  to  a  constantly  higher  tem- 
perature so  that  finally  after  years  of  continuous  slow 
increase  in  the  degree  of  heat,  they  can  stand  a  tempera- 
ture so  high  that  any  other  individual  not  acclimated 
would  certainly  die  if  subjected  to  it.  It  is  likewise 
known  that  the  same  species  of  Protozoa  are  found  in 
both  fresh  and  salt  water,  and  that  it  is  possible  to  ac- 
custom fresh- water  Amoebae  and  Infusoria  to  a  salt 
habitat  which  would  have  killed  them  at  the  start, — 
and  there  are  more  instances  of  the  same  kind.10 

10See  C.  B.  Davenport,  and  W.  E.  Castle,  "On  the  Acclimatisa- 


372  Appendix1 

One  feature  of  special  interest  to  us  is  the  fact  that 
the  new  conditions  of  the  environment  to  which  the 
animal  gradually  becomes  accustomed  tend  in  time  to 
become  his  optimum.  "This  individual  adaptation 
(e.  g.,  to  a  different  proportion  of  salt)  is  effected  in 
accordance  with  the  rule  that  the  conditions  of  density 
under  which  an  individual  is  living,  tend  to  become  in 
time  the  optimum  conditions  for  that  individual."  ll 

This  may  be  observed  even  in  plant  organisms. 
Plasmodia  of  the  Myxomycetes  die  when  plunged  sud- 
denly into  I  or  2%  glucose  solutions,  and  even  draw 
back  from  J^  or  Y^%  solutions,  and  yet  they  may 
gradually  become  accustomed  to  2%  solutions  so  that 
they  finally  show  by  their  behavior  that  they  prefer  their 
new  environment  to  the  original  one  without  glucose.12 

The  diatom  Navicula  brevis  ordinarily  shuns  even 
the  weakest  light  and  tries  to  hide  itself  in  the  darkest 
part  of  the  drop  of  water  in  which  it  is  being  observed. 
However,  if  a  culture  is  placed  in  the  bright  light  of  a 
window  for  two  weeks,  it  exhibits  exactly  the  opposite 
tendency  and  makes  for  the  brightest  part  of  the  drop 
as  soon  as  it  is  removed  again  to  its  former  position  in 
a  weak  light.13 

The  common  actinian  (Actinia  equina)  often  found 
clinging  to  rocks  in  all  possible  positions  with  relation  to 
the  force  of  gravity,  sometimes  with  the  axis  of  the 

tion  of  Organisms  to  High  Temperatures." — Archives  fur.  Entw.- 
Mech.  der  Organismen,  II,  2.  Heft,  July,  1895. — C.  B.  Davenport 
and  R.  V.  Neal,  "On  the  Acclimatisation  of  Organisms  to  Poisonous 
Chemical  Substances,"  loc.  cit.,  II,  4.  Heft,  Jan.  1896. 

11Davenport  and  Castle,  op.  cit.,  p.  241. 

12E.  Stahl,  "Zur  Biologic  der  Myxomyceten,"  Bot.  Zeit.,  Mar. 
7,  14  and  21,  1884,  p.  166. 

13Davenport  and  Castle,  op  cit.,  p.  246. 


Affective  Tendencies  373 

body  directed  upward,  sometimes  downward  and  some- 
times to  one  side,  seems  to  become  so  accustomed  to  its 
position  that  it  tries  to  assume  the  same  one  when  re- 
moved to  another  spot.  For  instance,  if  several  actin- 
ians  found  in  various  positions  are  collected  and  placed 
in  an  aquarium,  "they  show  in  attaching  themselves  a 
distinct  tendency  to  assume  the  same  position  they  had 
formerly  adopted."  14 

We  might  bring  forward  innumerable  other  ex- 
amples but  are  here  chiefly  concerned  with  pointing  out 
their  significance.  They  show  that  the  new  physiologi- 
cal state  arising  from  adaptation  to  the  new  environ- 
ment, when  once  it  has  supervened  and  has  existed  a 
certain  time  within  the  organism,  tends  thereafter  to 
preserve  or  restore  itself.  This  tendency  of  a  past 
physiological  state  to  remanifest  or  reproduce  itself  is 
nothing  but  the  tendency  inherent  in  every  mnemonic 
accumulation  to  "evoke"  itself  again.  Hence  it  is  a 
tendency  of  a  purely  mnemonic  nature. 

From  this  then  it  follows  directly  that  the  tendency 
to  physiological  invariability  from  which  originate,  as 
we  have  seen,  the  most  important  organic  affective  ten- 
dencies of  all  organisms  must  be  equally  mnemonic  in 
nature.  For  if  according  to  the  above  mentioned  ex- 
amples an  entirely  new  and  recent  physiological  state 
is  nevertheless  able  to  leave  behind  a  mnemonic  accumu- 
lation producing  a  distinct  tendency  to  its  own  restora- 
tion, it  is  easy  to  understand  that  in  proportion  as  the 
normal  physiological  state  persists  longer  it  must  possess 
a  correspondingly  stronger  mnemonic  tendency  toward 
its  restoration  whenever  it  is  disturbed. 

This   then    implies   that   each    of   the   innumerable 

14Pieron,  op  tit.,  p.   144. 


374  Appendix 

different  elementary  physiological  states,  of  which  each 
is  effective  at  one  definite  point  of  the  organism,  and  all 
combined  constitute  the  general  physiological  state, 
possesses  the  faculty  of  depositing  independently  a  "spe- 
cific accumulation/'  from  all  indications  similar  to  that 
deposited  in  the  brain  by  each  of  the  nervous  currents 
which  make  up  the  different  sensations  and  leave  behind 
a  mnemonic  residue  capable  of  being  reactivated  or 
revived,  By  "specific  accumulations"  of  the  various  ner- 
vous currents  we  mean  here  only  that  every  accumula- 
tion is  capable  of  giving  as  discharge  only  that  par- 
ticular specificity  of  the  nervous  current  by  which  this 
accumulation  has  itself  been  deposited. 

The  extension  of  this  faculty  of  "specific  accumula- 
tion" to  all  physiological  phenomena  in  general  accords 
with  the  hypothesis  that  nervous  energy  is  the  basis 
for  all  the  phenomena  of  life.  If  in  the  psycho- 
mnemonic  phenomena  properly  so  called  the  action 
of  nervous  energy  produced  by  "discharge"  or 
by  stimulation  of  the  respective  center  appears  in  the 
foreground,  whereas  the  specific  physico-chemical 
phenomena  accompanying  the  discharge  remain  in  the 
background  so  that  until  recently  they  were  quite  over- 
looked, that  would  be — according  to  the  fundamental 
concept  of  Claude  Bernard  on  the  essential  identity  of 
all  the  different  forms  of  irritability  of  living  matter— 
a  difference  of  degree  only  but  not  of  essence,  inasmuch 
as  true  physiological  phenomena  accompanying  the  re- 
spective stimulation  (muscular  contraction,  glandular 
secretion,  etc.)  appear  with  greater  distinctness,  where- 
as the  specific  nervous  phenomena  which  likewise  accom- 
pany this  physiological  activity  are  less  perceptible.  In 
this  way  we  have  tried  to  explain  the  fundamental  nine- 


Affective  Tendencies  375 

monic  property  of  all  living  substance  which  has  re- 
cently been  especially  emphasized  by  Hering,  Semon 
and  Francis  Darwin,  and  also  to  explain  the  most  essen- 
tial and  significant  biological  phenomena  proceeding 
from  it  either  directly  or  indirectly.15 

By  this  extension  of  the  mnemonic  faculty  to  all 
elementary  physiological  phenomena  we  now  obtain  a 
somatic  or  visceral  theory  of  the  fundamental  affective 
tendencies  in  the  sense  that  the  tendency  toward  physio- 
logical invariability  or  toward  the  restoration  of  this  or 
that  previous  physiological  state  corresponding  to  this 
or  that  previous  environment,  depends  on  innumerable 
elementary  specific  accumulations,  differing  from  point 
to  point  of  the  body  and  whose  combined  potential 
energy  would  form  as  it  were  a  "force  of  gravitation" 
toward  that  environment  or  those  conditions  which  make 
possible  the  preservation  or  restoration  of  the  combined 
physiological  system  represented  by  all  these  elementary 
accumulations. 

Naturally  in  organisms  supplied  with  nervous  sys- 
tems there  would  arise  and  be  gradually  developed  side 
by  side,  in  cooperation  with,  and  often  as  a  substitute 
for,  every  one  of  these  affective  tendencies  of  purely 
somatic  origin  and  seat,  the  affective  tendency  repre- 
sented by  the  corresponding  mnemonic  accumulations 
which  had  been  deposited  in  that  particular  zone  of  the 
nervous  system  directly  connected  with  the  respective 
points  of  the  body.  In  man,  for  instance,  this  zone 

15See  above  the  chapter  on  "The  Phenomena  of  Memory  and 
the  Vital  Phenomena."  See  also  "Die  Zentroepigenese  und  die 
nervose  Natur  der  Lebenserscheinung,"  Zeitschr.  f.  d.  Ausbau  d. 
Entwicklungs-lehre,  II,  1909,  Heft  8-9— "Das  biologische  Gedachtnis 
in  der  Energetik,"  Annalen  der  Natur  philosophic,  VIII,  and  Scientia, 
XI,  3,  1909. 


376  Appendix 

would  be  Flechsig's  Korperfuhlsphdre  to  which  in  cer- 
tain cases  may  also  be  added  the  frontal  zone.16 

Now  after  the  cerebral  mnemonic  accumulations 
had  arisen  phylogenetically  under  direct  somatic  action, 
they  would  finally  have  become  able  to  represent  by 
themselves,  even  if  all  connection  with  the  body  had 
been  severed,  those  former  affective  tendencies  to  which 
they  owed  their  origin.  And  indeed  this  is  true  be- 
cause of  the  two  fundamental  mnemonic  laws  of  (i) 
the  gradually  increasing  independence  of  the  part  with 
reference  to  the  whole  and  (2)  the  substitution  of  the 
part  for  the  whole,  which  arise  directly  from  the  fact 
that  every  elementary  specific  accumulation  when  once 
deposited  is  capable  of  an  independent  existence. 
Therefore  Sherrington's  "spinal"  dog,  for  instance, 
continued  to  experience  the  same  repugnance  to  the 
flesh  of  other  dogs,  to  exhibit  other  similar  affectivities 
and  even  the  same  emotions  as  the  normal  dog,  though 
all  of  them  are  undoubtedly  of  phyletic  somatic  origin.17 

But  this  cooperation  and  this  possibility  of  an  even- 
tual substitution  of  the  affective  tendency  whose  seat  is 
in  the  brain,  for  the  corresponding  affective  tendency 
of  somatic  origin,  does  not  prevent  the  former  from 
being  entirely  in  the  control  of  the  latter.  Therefore 
modern  psychology  generally  admits  that  the  affective 
life  "has  its  cause  below  in  the  variations  of  the  cenes- 

16P.  Flechsig,  Gehirn  und  Seele,  pp.  19,  21-22,  92,  99-100. 
Leipsic,  Veit.  1896. 

17See  C.  S.  Sherrington,  The  Integrative  Action  of  the  Nerv- 
ous System,  pp.  260-165.  London,  Constable,  1906.  Cf.  the  perti- 
nent discussion  of  these  experiments  by  Lloyd  Morgan,  Animal  Be- 
haviour, 2d  ed.,  p.  292,  London,  Arnold,  1908;  and  Revault  d'Al- 
lonnes,  Les  inclinations,  pp.  101  ff.,  Paris,  Alcan,  1908. 


Affective  Tendencies  377 

thesia,  which  is  itself  a  resultant,  a  combination  of  vital 
operations."  18 

Nor  does  it  in  the  least  prevent  affective  tendencies 
from  keeping  all  the  fundamental  properties  which 
they  owe  to  their  mnemonic  visceral  origin,  of  which 
the  most  important  are  first  the  possession  of  a  "diffuse" 
seat,  and  second  that  they  are  eminently  "subjective." 

For  every  stationary  physiological  system  in  equilib- 
rium with  regard  to  its  environment  permeates  the 
whole  organism  and  consequently  also  all  that  part  of 
the  brain  in  which  this  organism  is  reflected.  Accord- 
ingly, in  contrast  to  the  mnemonic  sense-accumulations 
each  of  which  to  all  appearances  has  a  seat  distinctly 
localized  at  a  single  point  or  in  a  single  center  of  the 
cortex  of  the  brain,  we  have  every  reason  to  conclude 
that  each  affective  tendency  is  made  up  of  an  infinitely 
large  number  of  different  elementary  mnemonic  accumu- 
lations, deposited  respectively  in  every  point  of  the  body 
and  in  every  corresponding  point  in  the  brain. 

To  this  mnemonic  physiological  origin  of  the  affec- 
tive tendencies  is  also  due  their  eminently  "subjective" 
character;  for  the  organism  is  equipped  potentially  with 
this  or  that  "idiosyncratic"  affective  tendency,  with  this 
or  that  "appetite,"  according  to  the  various  environ- 
ments or  conditions  in  which  the  species  and  the  in- 
dividual were  placed  for  a  longer  or  shorter  time  in 
the  past,  in  other  words  according  to  their  individual 
history. 

Hence  the  subjectivity  and  infinite  variety  manifest 
in  the  needs,  the  appetites  and  desires  and  consequently 
in  everything  that  furnishes  an  object  of  "affective 
evaluation." 

18Ribot,  Psych,   des  sent.,  p.    10. 


378  Appendix 

in. 

The  hypothesis  here  presented  of  the  mnemonic 
nature  of  the  affective  tendencies  in  general  is  further 
confirmed  by  other  examples  of  more  special  affec- 
tivities  which  have  also  originated  by  way  of  "habit" 
and  yet  bear  special  relations  to  the  environment  since 
they  affect  only  one  part  or  another  of  the  organism 
and  manifest  an  activity  only  periodically  or  intermit- 
tently. They  are  especially  in  evidence  in  the  higher 
animals  and  in  man  most  of  all. 

As  a  typical  instance  it  will  be  sufficient  to  consider 
maternal  love. 

Evidently  the  habit  of  having  certain  relations  of 
parasitism,  or,  in  general,  of  symbiosis,  with  the  progeny 
throughout  a  long  series  of  generations  has  become 
gradually  transformed  in  a  mnemonic  way  into  affective 
tendencies  towards  these  relations. 

"Comparative  ethology,"  says  Giard,  "shows  us  most 
clearly  that  the  relations  between  the  parent  organism 
and  its  progeny  are  in  principle  absolutely  the  same  as 
those  existing  between  a  parasite  and  the  animal  it  lives 
upon,  and  that  after  a  period  of  unstable  equilibrium  in 
which  one  or  other  of  the  two  associated  organisms 
suffers  to  the  advantage  of  its  companion  there  is  a 
tendency  to  the  establishment  of  a  definite  position  of 
mutual  (mutualiste)  equilibrium."  19 

This  is  true  for  instance  of  the  relations  of  internal 
incubation,  which  though  first  sought  and  effected  by 
the  embryo  itself  in  some  phase  of  its  development  for 
the  purpose  of  nutrition  or  some  other  advantage,  and 

19A.  Giard,  "Les  origines  de  Tamour  maternel,"  Revue  des 
idees,  April  15,  1905,  p.  256. 


Affective  Tendencies  379 

at  first  simply  endured  by  one  of  the  parents,  either 
father  or  mother,  finally  become  actual  "needs"  to  this 
parent. 

It  is  likewise  true  of  the  relations  of  external  incuba- 
tion (brooding)  which  arise  at  first  as  the  result  of  some 
particular  circumstance  and  in  this  way  become  a  habit. 
For  instance  the  attachment  manifested  by  the  female 
spider  Chiracanthium  carnifex  for  her  nest,  whether  it 
be  her  own  or  one  of  which  she  has  taken  possession, 
grows  with  time,  that  is  with  the  length  of  her  occu- 
pation of  it.  Hence  "mother  love"  seems  in  her  case 
to  be  really  nothing  but  her  attachment  to  a  home  to 
which  she  has  become  accustomed.20 

It  is  just  the  same  with  the  brooding  of  birds  and 
some  reptiles,  which  owes  its  origin  to  the  pleasant  sen- 
sation which  the  contact  with  the  fresh  eggs  brings  in 
the  feverish  condition  accompanying  the  egg-laying 
process,  but  which  by  habit  has  become  in  itself  an  in- 
stinctive inclination.21 

Finally  as  regards  lactation  the  young  have  gradually 
developed  secretions  in  the  lactiferous  glands  by  sucking 
the  secretions  of  the  perspiratory  glands  on  the  breast  of 
the  mother  brooding  over  them,  and  thus  they  have  at 
the  same  time  so  accustomed  the  mother  to  this  process 
that  lactation  finally  becomes  an  actual  need  for  her. 
"With  mammals  we  must  look  for  the  origin  of  the 
mutually  symbiotic  relations  which  unite  mother  and 
child  in  the  phenomenon  of  lactation.  The  physiological 
disorders  of  pregnancy  and  parturition  lead,  among  other 
very  curious  trophic  effects,  to  an  excessive  secretion  of 

20A.  Lecaillon,  "Sur  la  biologic  et  la  psychologic  d'une  araignee," 
.Innee  psychologique,   Annee    ice,  pp.    63-83.     Paris,   Nasson,    1904 
21Giard,   op.   cit.,  p.  266. 


380  Appendix 

the  mammary  glands  which,  as  we  know,  are  only  locally 
specialized  sebaceous  glands  of  the  skin.  The  young 
animal  in  taking  its  first  nourishment  thus  alleviates  the 
discomfort  of  the  female  and  becomes  a  means  toward 
the  comfort  of  its  mother."  22 

That  the  need  for  lactation  is  the  origin  of  maternal 
love  is  shown  by  the  fact  that  the  mother  who  is  deprived 
of  her  young  tries  to  replace  them  by  foster-nurslings. 
'The  necessity  of  getting  rid  of  a  troublesome  secretion 
is  powerful  enough  sometimes  to  cause  the  female  that 
lost  her  young  to  steal  the  progeny  of  another,  and  these 
robberies  have  been  performed  even  by  females  that  were 
still  suckling  their  own  young,  the  satisfaction  of  a  need 
leading  them,  as  is  generally  the  case,  to  seek  a  still 
greater  satisfaction  which  might  lead  even  to  excess."  23 

In  the  cases  observed  by  Lloyd  Morgan,  this  need  of 
the  mother  takes  the  form  of  a  mother  love  solicitous  for 
the  nourishment  of  her  young,  and  it  is  possible  that  it 
may  actually  represent  in  them  the  beginning  of  an  un- 
selfish attachment.  "Further,  I  have  seen  both  bitches 
and  cats  get  up  and  again  lie  down  so  as  to  bring  the 
teats  into  closer  proximity  to  the  mouth  of  any  young 
which  failed  to  find  them.  It  has  been  noticed  by  a  man 
who  is  a  remarkably  good  observer  and  lias  had  much 
to  do  with  animals,  and  also  by  myself,  that  when  a  lamb 
is  weakly  and  fails  to  find  the  teat,  the  mother  not  in- 
frequently uses  its  shoulders,  head  and  neck  as  a  lever 
to  place  the  lamb  on  its  legs;  and,  having  accomplished 
this,  straddles  over  the  lamb,  and  brings  the  teats  against 


22Giard,  op.  cit.,  pp.  269-270. 
23Giard,  loc  cit.,  p.  270. 


Affective  Tendencies  381 

its  lips;  and  these  efforts  are  continued  until  the  little 
animal  sucks."  24 

This  example  is  very  significant  for  it  shows  clearly 
how  the  necessity  for  the  elimination  of  the  milk  must 
end  in  arousing  an  attachment  for  the  nursling  as  the 
customary  means  for  attaining  this  end,  just  as  we  have 
seen  that  the  need  for  the  elimination  of  the  germinal 
substance  must  lead  to  an  affectivity  for  the  other  sex, 
here  again  as  the  customary  means  to  effect  this 
elimination. 

Just  as  "sexual  attraction"  ceases  after  the  elimina- 
tion of  the  germinal  substance,  so  also  does  "mother 
love"  disappear  as  soon  as  the  need  for  lactation  is  no 
longer  felt.  "Maternal  affection  does  not  generally  sur- 
vive the  causes  which  produced  it  and  only  vague  traces 
of  it  are  noticeable  after  lactation  has  ceased."  25 

Finally,  the  fact  that  the  mother's  affection  is  stronger 
than  that  of  the  father,  and  that  the  parents'  love  for 
their  children  is  stronger  than  that  of  the  children  for 
their  parents  confirms  the  hypothesis  that  all  these  affec- 
tivities  have  arisen  exclusively  by  way  of  habit,  for  it 
shows  that  affection  for  those  with  whom  we  have  cer- 
tain relations  is  the  more  intense  the  more  numerous 
and  prolonged  these  relations  are.  "Among  animals  as 
a  whole,"  remarks  Ribot,  "paternal  love  is  rare  and  in- 
constant and  among  the  lower  representatives  of  man- 
kind it  is  a  feeble  sentiment  and  forms  but  a  slight 
bond."  26  Paternal  love  exists  only  where  the  union  of 
the  sexes  is  close,  that  is,  where  the  communal  life 

24Lloyd  Morgan,  Habit  and  Instinct,  p.  115,  New  York,  ArnoM. 
1896. 

25Giard,   op.  cit.,  p.  273. 
26Ribot,  psych,  des  sent.,  285. 


382  Appendix 

"creates  a  current  of  affection  because  of  services  ren- 
dered." 27 

"Every  one  recognizes/'  says  Pillon  in  his  turn,  "that 
the  love  of  parents  for  their  children  exceeds  in  intensity 
the  children's  love  for  the  parents,  and  that  of  the  two 
parents  it  is  the  mother  whose  love  is  stronger  for  her 
child.  .  .  .  The  reason  is  that  in  the  mother's  case  much 
more  than  with  the  father  the  love  for  the  child  is  nour- 
ished and  stimulated,  because  of  her  special  functions, 
that  is,  by  the  constant  performance  of  the  actions  it 
dictates."  28 

But  mother-love  and  mutual  love  within  the  family  in 
general,  owing  its  origin  to  certain  relations  grown  into 
habit,  represents  only  one  particular  case  of  a  universal 
law.  For  every  other  relation  to  person  or  things  (no 
matter  how  special)  which  becomes  in  the  slightest 
degree  a  habit  finally  appears  for  this  very  reason  as 
something  "desired."  In  every  environmental  relation 
whether  general  or  particular  is  verified  Lehmann's  law 
of  the  "indispensability  of  the  customary,"  which  this  in- 
vestigator established  for  every  stimulus  to  which  one 
becomes  accustomed  and  whose  cessation  arouses  a  need 
for  its  presence.29 

"I  have  a  small  clock  in  my  room,"  a  friend  once 
wrote  to  G.  E.  Miiller,  "which  will  not  run  quite  twenty- 
four  hours  with  one  winding.  It  often  happens  therefore 
that  it  stops.  Whenever  this  occurs  I  notice  it  at  once, 
whereas  of  course  I  do  not  hear  it  at  all  when  it  is 


27Ribot,  Psych,  des  sent.,  p.  286. 

28F.  Pillon,  "Sur  la  memoire  et  Imagination  affective,"  Annee 
bhilosophique,  XVII,  1903,  pp.  69-70.  Paris,  Alcan,  1907. 

*»A.  Lehmann,  Die  Hauptgesetze  des  menschlichen  Gefiihlslebens, 
pp.  194  ff.  Leipsic,  Reisland,  1892. 


Affective  Tendencies 


running.  The  first  time  this  occurred  the  sensation  was 
somewhat  as  follows :  it  happened  that  I  was  suddenly 
aware  of  a  very  indefinite  unrest,  a  lack  of  something 
without  being  able  to  say  just  what  the  matter  was.  Not 
until  after  some  reflection  did  I  discover  the  cause  in 
the  stopping  of  my  clock."  30 

Moreover  each  of  us  has  doubtless  had  opportunity 
to  observe  how  things  which  are  disagreeable  at  first 
finally  become  attractive  from  custom,  and  how  such 
habits  assumed  in  the  course  of  man's  life  become  as  per- 
emptory "needs"  as  those  which  we  call  natural  needs. 
"Smokers,  snuff-takers,  and  those  who  chew  tobacco, 
furnish  familiar  instances  of  the  way  in  which  long  per- 
sistence in  a  sensation  not  originally  pleasurable,  makes 
it  pleasurable — the  sensation  itself  remaining  unchanged. 
The  like  happens  with  various  foods  and  drinks,  which, 
at  first  distasteful,  are  afterwards  greatly  relished  if  fre- 
quently taken."  31 

Thence  arises  the  hankering  after  certain  customary 
things  which  we  suddenly  miss :  "In  some  animals  there 
is  produced  a  condition  resembling  nostalgia,  expressing 
itself  in  a  violent  desire  to  return  to  former  haunts,  or 
in  a  pining  away  resulting  from  the  absence  of  accus- 
tomed persons  and  things."  32 

Mere  habit,  therefore,  is  enough,  as  we  have  seen  in 
the  case  of  family  love,  to  cause  other  similar  affectivities 
also  to  originate  and  take  root.  Such  are  gregariousness, 
sociability,  friendship,  and  the  like:  "The  perception  of 

30G.  E.  Miiller,  Zur  Theorie  der  Sinnlichen  Aufmerksamkeit, 
p.  128,  Leipsic,  Edelmann. 

"Herbert  Spencer,  The  Principles  of  Psychology,  4th  ed.,  I, 
287.  London,  Williams  and  Norgate,  1899. 

S2Th.  Ribot,  Essay  on  the  Creative  Imagination,  p.  95.  Chi- 
cago, The  Open  Court  Publishing  Company,  1906. 


384  Appendix 

kindred  beings,  perpetually  seen,  heard,  and  smelt,  will 
come  to  form  a  predominant  part  of  consciousness — so 
predominant  a  part  that  absence  of  it  will  inevitably 
cause  discomfort."  33 

Finally  we  are  all  well  aware  of  the  powerful  influence 
of  the  habits  of  life  current  in  any  family  circle  during 
the  earliest  years  of  a  child's  life — "nurture"  in  its  broad 
sense,  as  Galton  would  say — because  from  these  habits 
arise  and  grow  the  feelings  and  moral  tendencies  which 
remain  impressed  upon  the  whole  life  as  though  they 
were  "innate."  34 

In  short  from  these  few  instances  adduced  simply  in 
explanation  of  our  position,  we  see  how  profound  is  the 
truth  contained  in  the  saying  that  habit  is  a  "second 
nature." 

But  if  to  a  certain  extent  we  can  see  the  most  diverse 
tendencies  originate  by  way  of  habit  before  our  very  eyes, 
then  we  may  also  attribute  a  similar  mnemonic  origin  to 
all  affective  tendencies,  since  the  nature  of  innate  tenden- 
cies differs  in  no  wise  from  that  of  acquired  tendencies. 
Very  similarly  in  the  case  of  morphological  evolution  we 
may  consider  that  the  Lamarckians  are  quite  justified  in 
drawing  from  the  few  observable  cases  of  adaptation  ac- 
quired during  life,  the  conclusion  that  the  entire  structure 
of  the  organism  owes  its  existence  to  an  infinite  number 
of  similar  functional  adaptations. 

Hence  we  may  complete  the  saying  quoted  above  with 
the  phrase  that  on  the  other  hand  "nature"  is  nothing 
but  a  "former  habit." 

33 Spencer,  op.  cit.,  II,  626. 

34Francis  Galton,  Inquiries  into  Human  Faculty  and  Its  Devel- 
opment, pp.  208-216.  London,  MacMillan,  1883. 


Affective  Tendencies  385 


IV. 

The  hypothesis  of  the  mnemonic  origin  and  nature  of 
all  affective  tendencies  finds  still  further  support  in  a 
property  which  is  inherent  in  all  of  them,  namely  their 
''transference"  which  likewise  is  itself  essentially  mne- 
monic and  by  which  all  other  affectivities  are  derived 
from  those  of  direct  mnemonic  origin  and  thus  come  to 
have  an  indirect  mnemonic  origin  (Ribot's  "law  of 
transference"). 

For  in  consequence  of  the  "substitution  of  a  part  for 
the  whole,"  a  fundamental  mnemonic  principle  frequently 
mentioned  above,  it  happens  that  merely  parts  or  frag- 
ments of  certain  environmental  relations,  striven  for 
originally  in  their  totality,  or  that  "analogous"  environ- 
mental relations,  i.  e.,  those  that  are  only  partly  similar 
to  one  desired,  or  that  environmental  relations  constituting 
"means"  suited  to  the  attainment  of  an  "end"  and  there- 
fore its  necessary  precursors,  or,  in  fine,  that  environmen- 
tal relations  which  constantly  accompany  this  "end," 
evoke  the  same  affectivity  as  the  original  "end"  itself. 
Hence  this  affe^tivity  is  "transferred"  from  the  whole  to 
the  part,  and  this  attachment  for  the  part  then  becomes 
so  much  stronger  that  this  partial  relation  which  is  first 
sought  as  a  substitute  for  the  whole  finally  constitutes 
in  its  turn  an  habitual  environmental  relation  hencefor- 
ward desired  or  sought  for  its  own  sake  quite  apart  from 
the  real  and  original  affective  "transference." 

This  is  the  case  for  instance,  as  has  been  mentioned 
above,  with  regard  to  copulation,  the  customary  means 
for  the  elimination  of  germinal  substance,  and  also  with 
regard  to  the  secondary  sexual  relations  as  phenomena 
usually  accompanying  copulation.  The  "conquest"  of 


386  Appendix 

the  other  sex  though  only  a  necessary  means  for  the  sat- 
isfaction of  sexual  appetite  finally  becomes  with  certain 
individuals  an  end  in  itself.  The  pleasure  in  seducing 
for  its  own  sake,  the  "sexual  vanity"  of  both  male  and 
female  and  the  other  similar  affectivities  are  further 
instances. 

The  case  is  the  same  with  the  tearing  to  pieces  of  prey 
which  was  originally  the  customary  means  for  satisfying 
hunger  but  finally  gave  place  to  cruelty  for  cruelty's  sake. 

"One  half  of  the  animal  race  live  upon  prey;  and  as 
it  is  delightful  to  eat  so  it  must  be  delightful  to  kill. 
Pleasurable  also  must  be  all  the  signs  of  discomfiture, 
the  helpless  struggles  and  agonized  gestures  of  the 
victim/'  35 

In  man  the  love  of  victory  for  its  own  sake,  ambi- 
tion, thirst  for  power,  desire  for  fame  and  glory,  the 
endeavor  to  surpass  his  fellows,  are  all  derived  as  con- 
sequences of  further  transference. 

In  these  and  all  other  similar  cases  of  affective  trans- 
ferences to  environmental  relations  constantly  becoming 
less  material  and  more  moral,  besides  the  real  proper 
affective  transference  which  transforms  the  part  into  a 
new  "end,"  there  is  always  involved  in  man  and  in  the 
higher  animals  the  cooperation  of  their  own  intellectual 
development. 

For  the  intellect  is  constantly  discovering  new  and 
unsuspected  similarities  between  the  most  diverse  phe- 
nomena, even  between  material  and  ethical  phenomena, 
extending  the  same  affectivities  to  the  one  class  that  are 
valid  for  the  other;  just  as  disgust  for  certain  foods 
characterized  by  taste  or  odor  as  unwholesome  extends 

35Alexander  Bain,  The  Emotions  of  the  Will,  4th  ed.,  London, 
Longmans  Green,  1899,  p.  65. 


Affective  Tendencies 


to  certain  objects  which  can  only  be  touched  or  seen 
(viscous  bodies),  and  then,  carrying  the  analogy  still 
farther,  even  to  simple  "objects"  or  relations  of  an 
ethical  order.36 

At  the  same  time  inasmuch  as  the  intellect  foresees 
with  constantly  increasing  sharpness  the  external  phe- 
nomena to  be  expected  as  effects  of  given  causes,  it  con- 
tinues to  devise  new  means  more  indirect  and  more 
complex  for  attaining  its  end,  and  thereby  to  open  a 
broader  sphere  of  efficiency  for  "affective  transference." 
For  instance  the  weapon  which  was  invented  by  man  as 
means  for  self-preservation  has  rendered  possible  an 
affective  transference  to  itself  which  is  characteristic  of 
the  warrior  and  the  hunter;  and  the  earth  which  the 
agriculturist  has  utilized  to  provide  his  own  nourishment 
has  made  possible  that  intense  love  for  the  soil  frequent 
among  farmers. 

Furthermore,  since  the  intellect  also  foresees  with  in- 
creasing certainty  internal  physical  processes,  it  calls  into 
being  a  large  number  of  new  affectivities  destined  to  pre- 
vent possible  future  affective  tendencies  from  remaining 
unsatisfied.  For  instance  the  anticipation  of  future 
hunger  gives  even  the  satiated  man  the  inclination  to  lay 
up  food  that  is  left  from  a  meal,  and  to  keep  it  in  his 
possession.  Thus  arises  in  general  the  sense  of  owner- 
ship, and  in  the  same  way  the  anticipation  of  the  in- 
numerable other  desires  which  civilized  man  cherishes 
today  excites  in  him  an  intense  longing  for  wealth,  covet- 
ousness  and  similar  passions.37 

Finally,  the  intellect  renders  possible  that  infinite  vari- 

3eRibot,  Psych,  des  sent.,  p.  212. — Essai  sur  les  passions,  pp.  65  ff. 
37 Spencer,  Princ.  of  Psychol,  I,  488  f.— Ribot,  Psychol.  des  sent., 
no,  269-270. 


388  Appendix 

ety  of  shades  of  which  affective  tendencies  are  capable  in 
man.  For  since  it  is  able  to  observe  from  different 
points  of  view,  simultaneously  or  nearly  so,  all  environ- 
mental relations  even  when  only  slightly  associated,  it 
can  evoke  diverse  affectivities  at  the  same  time,  and  these, 
as  Bain  would  say,  by  association,  combination,  con- 
fluence, interference  or  mutual  partial  inhibition,  finally 
produce  an  exceedingly  complex  affectivity  which  is 
therefore  capable  of  showing  the  finest  imaginable  grada- 
tions from  one  case  to  another  according  to  the  number 
and  character  of  its  component  parts. 

Thus,  for  Instance,  fear,  anxiety  and  kindred  feelings 
had  already  developed  in  animals  from  the  instinct  of 
self-preservation  in  its  purely  defensive  form;  but  in  man 
this  latter  gave  rise  also  to  all  the  propitiatory  affectivities 
in  innumerable  varieties  and  shades,  such  as  prostration, 
humility,  hypocrisy,  flattery  and  the  like.  Even  the  re- 
ligious sentiment  in  its  lowest  forms  is  a  direct  conse- 
quence of  this  propitiatory  affectivity,  while  the  loftier 
religious  sentiment  and  the  kindred  feeling  experienced 
in  the  presence  of  the  sublime  are  more  highly  developed 
and  more  complete  forms  of  the  same  thing.38 

Similarly  from  the  instinct  of  self-preservation  in  its 
double  aspect,  offensive  and  defensive  at  the  same  time, 
had  already  developed  in  the  higher  animals  the  instinct 
to  attack  and  all  the  different  varieties  of  counter-attack ; 
but  in  man  this  instinct  has  assumed  the  most  varied 
forms  and  shades  from  deepest  hatred  to  a  scarcely  per- 
ceptible antipathy,  from  rapacity  to  the  merest  envy,  and 
from  the  most  violent  thirst  for  revenge  to  the  slightest 
resentment.  The  noble  sentiment  of  justice  is  a  very 

38For  instance,  see  Ribot,  Psych,  des  sent,  p.  100,  and  E.  Rignano, 
*'II  fenomeno  religiose/'  Scientia,  XIII,  i,  1910. 


Affective  Tendencies  389 

remote    and    hardly    distinguishable    derivative    of    the 
same  instinct.39 

How  high  may  be  the  degree  of  complexity  which  can 
thus  be  attained  is  attested,  for  instance,  by  maternal  love 
which  has  grown  from  the  purely  bodily  necessity  for  lac- 
tation to  the  tenderest  feelings  of  the  noblest  self-denial, 
and  especially  also  by  conjugal  affection  which  has  been 
transformed  from  coarse  brutal  sexual  appetite  to  an 
harmonious  cooperation  of  the  gentlest  and  most  delicate 
moral  affectivities.40 

Yet  it  is  easily  comprehensible  that  it  would  be  use- 
less, and  impossible  to  stop  here  to  investigate  all  of  the 
affectivities  and  their  slightest  shades  which  have  arisen 
and  in  this  way  attained  their  development  in  the  higher 
animals  and  especially  in  man.  Let  these  few  indica- 
tions suffice  to  render  intelligible  the  fact  that  as  soon 
as  the  organism  has  acquired  in  the  direct  mnemonic 
way  a  stock  of  affective  tendencies  and  the  intellect  has 
attained  its  proper  development,  the  number  of  affec- 
tivities which  may  be  derived  by  "transference"  and  by 
"combination,"  that  is  to  say,  by  indirect  mnemonic 
means,  is  infinite. 

v. 

But  few  words  are  needed  to  indicate  the  place  of 
affective  tendencies  among  those  fundamental  physical 
phenomena  which  are  most  closely  connected  with  them, 
such  as  the  emotions,  the  will,  and  the  states  of  pleasure 
and  pain. 

Emotions  are  only  sudden  and  violent  modes  of  acti- 

39See  Bain,  The  Emotions  and  the  Will,  pp.  117  f.— Ribot,  Psych, 
des  sentiments,  pp.  229  f.,  271  f. — Problemes  de  psychologic  affective, 
chap.  Ill,  "L'antipathie,"  Paris,  Alcan,  1910. 

40Spencer,  op  cit.,  I,  487  f. 


390  Appendix 

vation  of  those  very  accumulations  of  energy  of  which  the 
affective  tendencies  consist. 

Of  course  it  is  not  always  possible  clearly  to  distin- 
guish affective  tendencies  from  emotions  since  the  former 
are  perceptible  neither  objectively  nor  subjectively  as  long 
as  they  remain  in  a  potential  state,  but  become  so  at  their 
activation  which,  when  sudden  and  violent,  represents 
the  corresponding  emotion.  But  the  importance  and 
necessity  of  distinguishing  accurately  between  emotions 
and  affective  tendencies — a  distinction  however  which  is 
usually  entirely  neglected  by  most  psychologists — lies  in 
the  fact  that  one  and  the  same  affective  tendency  may  ac- 
cording to  external  circumstances  give  rise  to  the  most 
diverse  emotions,  to  the  most  diverse  degrees  of  their 
intensity,  or  even  to  no  emotion  at  all  properly  so  called. 
For  instance  if  we  see  a  vehicle  approaching  at  a  distance 
we  quietly  step  aside  out  of  the  way,  but  if  it  appears 
suddenly  before  us  at  an  abrupt  turn  in  the  street  we 
feel  a  strong  emotional  shock.  And  the  same  affective 
tendency  of  the  dog  towards  a  piece  of  meat  can  give 
rise  to  flight,  anger,  or  the  careful,  coolly  calculated  search 
for  a  safe  hiding  place,  according  to  the  circumstances 
under  which  his  dainty  meal  is  endangered. 

In  short,  every  emotion,  as  Stout  rightly  emphasizes, 
presupposes  an  affective  tendency,  but  the  reverse  does 
not  follow;  for  an  affective  tendency  even  when  in  full 
activation  need  not  always  imply  any  emotion.41 

Every  affective  tendency  "impels"  to  action,  that  is,  it 
not  only  "starts"  but  really  "impinges"  upon  the  organs 
of  motion  either  directly  as  in  the  lower  organisms  or 
by  the  aid  of  the  nervous  system  as  in  the  higher. 

41  See  G.  F.  Stout,  A  Manual  of  Psychology,  2d.  ed.,  p.  305, 
London,  1907.  • 


Affective  Tendencies  391 

Therefore  from  the  first  moment  of  its  activation  it  has 
the  appearance  of  a  "movement  in  the  nascent  state" 
(Ribot). 

If  its  activation  is  sudden  and  intense  the  resulting 
activity  of  the  motor  muscles  is  accompanied  by  that  of 
all  the  viscera.  This  "visceral  cooperation"  which  thus 
takes  place  in  connection  with  the  emotions  properly  so 
called,  is  not,  as  Sherrington  believes,  due  solely  to  the 
fact  that  the  rapidity  and  intensity  with  which  the  muscles 
are  set  in  motion  induces  the  immediate  action  of  the 
viscera  which  furnish  the  muscles  wth  the  material  for 
their  energy,  but  also  and  especially  because  there  is  an 
overflow  of  nervous  energy,  which  suddenly  released  in 
great  quantities  acts  like  a  flood,  and  pours  forth  in  nu- 
merous other  tracks  than  those  closely  connected  with  the 
locomotor  apparatus.42 

And  this  visceral  commotion  thus  produced  as  a  result 
of  the  sudden  intense  impulse,  according  to  the  well- 
known  theory  of  James,  Lange  and  Sergi,  finds  its  cen- 
tripetal echo  in  the  brain  in  the  form  of  an  emotion.43 

Hence  it  is  the  affective  tendency  which  impels  us  and 
not  the  emotion  as  Sherrington  maintains  in  accordance 
with  the  prevalent  confusion  between  affective  tendency 
and  emotion  which  cannot  be  too  greatly  deplored,  and 
the  emotion  is  only  the  reaction  of  a  too  rapid  and  intense 
manifestation  of  this  tendency. 

On  the  other  hand  if  on  account  of  external  condi- 
tions or  the  psychic  disposition  of  the  individual  the  acti- 
vation of  the  affective  tendency  takes  place  neither  too 

42See  Sherrington,  The  Integrative  Action  of  the  Nervous  Sys- 
tem, pp.  265  f. 

43See  the  famous  article  of  W.  James,  "What  is  an  Emotion?" 
Mind,  April,  1884,  pp.  188-205.— Revault  d'Allonnes,  Les  inclinations, 
108  f. 


392  Appendix 

suddenly  nor  with  too  great  intensity,  then  only  are  the 
requisite  muscles  called  into  play  without  any  emotion. 
Thus  the  amount  of  useful  work  accomplished  as  a  result 
of  the  discharge  of  the  affective  tendency  is  greater  in 
inverse  proportion  to  the  amount  lost  in  the  coordinated 
movements  of  a  purely  emotional  significance.  This  is 
the  reason  why  we  generally  observe  the  greatest  deter- 
mination, the  most  tenacious  persistence  in  transactions, 
the  most  intense  and  feverish  activity  in  "unemotional" 
individuals.44 

As  regards  the  will,  an  act  of  volition  takes  place 
whenever  an  affective  tendency  directed  towards  a  future 
goal  triumphs  over  an  affective  tendency  whose  aim  is 
for  the  present;  in  other  words,  whenever  a  far-sighted 
affectivity  is  victorious  over  a  short-sighted  one.  It  is 
not  the  man  who  sweating  and  panting  after  a  long  run 
throws  himself  down  to  drink  eagerly  from  a  spring  who 
exercises  an  act  of  volition,  but  rather  the  one  who  for- 
bears to  slake  his  burning  thirst  for  fear  of  a  greater 
future  evil.  Likewise  no  act  of  volition  is  exerted  when 
an  exhausted  wanderer  throwrs  himself  dowrn  to  sleep, 
but  rather  when  a  mountain  climber  overcomes  exhaus- 
tion in  order  to  reach  the  desired  goal.  And  the  act  of 
a  man  who  on  a  momentary  impulse  falls  upon  his  oppo- 
nent at  the  slightest  provocation  with  hard  words  and 
fisticuffs  does  not  demand  any  will  power,  as  does  the 
conduct  of  the  man  who  bridles  his  just  anger  in  order 
coolly  to  estimate  to  its  remotest  consequences  the  most 
appropriate  procedure  to  enter  upon  against  the 
offender.45 

44See  Revault  d'Allonnes,  Les  inclinations,  pp.  207  f. 
45Cf.  E.  Meumann,  Intelligenz  and  Wille,  pp.  181   f.    (Leipsic, 
Quelle  und  Meyer,  1908),  although  differing  in  many  points. 


Affective  Tendencies  393 

Essentially  then  the  will  is  nothing  else  than  a  true 
and  proper  affective  tendency  which  checks  other  affective 
tendencies  because  it  is  more  far-sighted  and  which  in  its 
turn  impels  to  action  like  all  affective  tendencies.  "There 
is  present  in  the  action  of  will  some  desire  of  a  good  to 
be  obtained  or  of  an  evil  to  be  shunned,  which  imparts 
its  driving  force."  46 

Two  extreme  instances  deserve  special  mention,  for 
they  include  all  other  cases.  The  first  of  these  may 
again  be  divided  into  two. 

Sometimes  one  of  the  affective  tendencies  is  so  strong 
and  persistent  that  it  constantly  outweighs  all  others;  it 
checks  them  if  it  is  contrary  to  them  and  strengthens  them 
if  it  is  in  harmony  with  them.  Such  an  "hypertrophied" 
affective  tendency  is  called  "passion"  (Ribot,  Renda).  If 
it  is  directed  towards  some  present  aim  we  say  that  it 
overthrows  the  will  because  it  successfully  withstands  the 
inhibitive  effect  of  every  other  affective  tendency  directed 
towards  the  future;  if  on  the  other  hand  its  own  aim  is 
in  the  future,  an  "ideal"  whose  attainment  may  require 
the  work  of  a  lifetime,  then  we  say  that  the  individual 
is  persevering,  stubborn,  unyielding,  endowed  with  an 
iron  will,  because  every  other  opposed  affective  tendency 
directed  toward  an  immediate  end  dashes  in  vain 
against  it. 

On  the  other  hand  it  sometimes  happens  that  the  two 
conflicting  affective  tendencies  are  evenly  balancd.  At 
one  moment  the  far-sighted  tendency  gains  greater  force 
and  seems  to  triumph  by  turning  the  mind  to  new  conse- 
quences in  the  future,  but  the  next  instant  the  short- 
sighted tendency  discovers  new  or  more  clearly  recog- 

46Maudsley,  The  Physiology  of  Mind,  p.  389.  London,  Mac- 
Millan,  1876. 


394  Appendix 

nized  aspects  in  the  object  desired  for  the  time  being, 
and  becomes  more  intense,  threatening  again  to  gain  the 
upper  hand.  The  individual  then  falls  in  a  state  we  call 
''indecision."  When  a  philosopher  discovers  by  intro- 
spection that  he  is  in  this  situation,  he  will  easily  realize 
that  both  affectivities  exist  together  within  him,  that  they 
are  "flesh  of  his  flesh,"  and  that  the  slightest  and  most 
insignificant  physical  occurrence  is  enough  to  cause  either 
one  to  gain  ascendency  over  the  other.  It  is  clear  that 
he  can  easily  fall  a  prey  to  the  illusion  that  nothing  at 
all,  any  chance  breath  of  wind,  is  enough  to  give  one  the 
preponderance  over  the  other.  This  is  the  subjective 
illusion  of  free  will  which  for  many  centuries  has  con- 
stituted the  greatest  and  most  difficult  problem  that  philos- 
ophy has  been  called  upon  to  solve. 

Finally  to  come  to  the  consideration  of  "pleasure" 
and  "pain,"  it  is  the  merit  of  the  modern  psychological 
school  that  it  has  shown  the  fallacy  of  Bain's  theory  that 
the  fundamental  fact  of  animal  life  is  the  pursuit  of 
"pleasure,"  in  other  words,  the  search  for  everything 
pleasant  and  the  avoidance  of  everything  unpleasant; 
and  on  the  other  hand  that  it  has  clearly  emphasized  that 
the  conditions  of  pleasure  and  pain  represent  only  the 
superficial  part  of  the  affective  life,  "of  which  the  deep 
element  consists  in  affective  tendencies,  positive  or  nega- 
tive. .  .  .  These  are  the  elementary  processes  of 
affective  life,  of  which  pleasure  and  pain  represent  only 
the  satisfaction  or  failure."  47 

Since  an  activation  of  nervous  energy  accompanies 
every  "satisfaction"  of  any  affective  tendency,  and  every 
"disappointment"  corresponds  to  an  interruption  or  ces- 
sation of  this  energy,  pleasure  really  corresponds  to  every 

47Ribot,  Psychol.  des  sent.,  p.  2.—Probl.  de  psych,  aff.,  p.  16. 


Affective  Tendencies  395 

state  of  discharge  or  activation  of  the  nervous  or  vital 
energy,  and  pain  to  every  state  of  inhibition  or  suppression 
of  it. 

In  fact  "painful"  is  every  act  inhibitive  of  certain 
nervous  activities;  "unpleasant"  every  too  perceptible 
change  of  surrounding  conditions  which  renders  impos- 
sible the  continuance  of  the  hitherto  stationary  physio- 
logical state,  "agonizing"  every  sudden  and  violent 
change  of  environment  which  brings  about  the  complete 
stoppage  or  destruction  of  life  in  one  or  another  part  of 
the  organism,  and  "sad"  is  the  individual  when  there  is 
a  general  diminution  of  vital  functions  within  his 
organism. 

Inversely,  it  is  "pleasant"  to  exercise  one's  muscle  in 
play  and  sport;  the  cessation  of  a  strained  condition  of 
the  soul  is  a  "relief,"  the  return  to  an  accustomed  environ- 
ment and  the  resumption  of  habits  is  "welcome,"  and  in 
general  full  of  "joy"  and  "pleasure"  is  every  state  in 
which  the  organism  experiences  a  greater  activity  of 
nervous  energy.48 

It  is  sufficient  here  to  indicate  that  the  theory  of  the 
mnemonic  origin  of  all  affective  tendencies  which  we  have 
endeavored  to  explain  and  substantiate  in  this  essay, 
offers  a  new  argument  in  support  of  the  modern  psycho- 
logical views  with  regard  to  the  inmost  nature  of  pleasure 
and  pain.  For  in  assigning  to  these  affective  tendencies 
the  nature  of  mnemonic  accumulations  it  implies  that  the 
fundamental  principle  of  affective  life  can  be  nothing 
but  the  tendency  to  activation  inherent  in  these  accumu- 

48See  Ribot,  Psych,  des  sent.,  Part  I,  chapters  I-III,  especially 
pp.  52  f.  and  83  f. — W.  Ostwald,  Vorlesungen  iiber  Natur philosophic, 
pp.  388  ff.  Leipsic,  Veit.  1905 


396  Appendix 

lations,  such  as  exists  also  in  every  other  accumulation 
of  potential  energy,  and  that  therefore  pain  and  pleasure, 
pleasant  and  painful  states,  can  be  nothing  but  the  super- 
ficial and  subjective  side  of  this  activation  or  of  its 
inhibition. 

VI. 

Before  terminating  these  few  notes  upon  the  nature 
of  affective  tendencies,  we  shall  add  a  few  remarks, 
which  seem  to  us  indispensable,  on  the  fundamental 
character  of  these  tendencies,  according  to  which  they 
constitute  a  force,  so  to  speak,  with  a  definite  end  to  be 
attained  but  with  the  path  to  be  followed  left  unde- 
termined. 

Affective  tendencies  owe  this  property  of  gravitating 
toward  an  end  while  the  means  remain  undecided,  to  the 
circumstance  that  they  depend  on  the  existence  in  a 
potential  state  of  a  certain  general  or  local  physiological 
system  or  state,  which  was  determined  in  the  past  by  the 
outside  world  as  a  whole  or  by  individual  particular  rela- 
tions to  this  outside  world,  and  which  now  like  every 
other  potential  energy  simply  endeavors  to  reactivate 
itself  as  soon  as  it  is  released  by  the  persistence  or  recur- 
rence of  even  a  small  part  of  this  environment  or  these 
environmental  relations.  For  the  result  of  the  existence 
of  this  tendency  is  that  the  organism  gravitates  toward 
this  environment  or  these  environmental  relations  ren- 
dering possible  the  recurrence  of  this  physiological  state, 
but  it  does  not  imply  any  "impulse"  toward  or  "impinge- 
ment" upon  any  one  of  the  series  of  passing  physiological 
states  or  movements  which,  even  if  they  were  capable  of 
eventually  bringing  the  organism  back  to  the  desired  en- 
vironment, nevertheless  have  nothing  in  common  with 


Affective  Tendencies  397 

the  definitive  physiological  state  itself  which  corresponds 
to  this  environment. 

Only  from  the  moment  when  one  series  of  move- 
ments happens  to  bring  the  organism  back  to  the  desired 
environmental  relations  earlier  than  another  one,  will 
it  have  acquired  an  advantage  over  the  others,  and  this 
result  may  be  expressed  by  saying  that  the  affective  ten- 
dency has  exercised  a  "choice"  (James,  Baldwin  and  the 
American  school  in  general). 

Hence  it  is  only  from  that  moment  that  the  affective 
tendency  will  by  mnemonic  association  constitute  a  force 
which  "impels"  these  movements  toward  the  end,  just 
as  certain  reflex  movements  "impinge"  on  one  another 
(Sherrington).  And  only  from  that  moment  will  these 
movements  (so  long  as  they  have  not  become  mechanical 
in  the  form  of  reflexes)  be  determined  exclusively  under 
the  pressure  of  the  corresponding  affectivity  or  the  equiv- 
alent "act  of  the  will." 

However,  until  this  takes  place  the  affectivity  betrays 
no  tendency  at  all  to  discharge  in  one  path  rather  than 
in  another,  hence  the  great  difference  between  the  affec- 
tive tendency  or  act  or  will  on  the  one  hand,  and  the 
reflex  movement  on  the  other.  This  reflex  movement,  by 
means  of  which  the  act  so  "chosen"  when  often  re- 
peated becomes  by  mnemonic  accumulation  gradually 
mechanical  and  quite  independent  of  the  whole,  repre- 
sents a  tendency  to  discharge  along  one  single  given  path 
which  is  determined  in  advance.  It  is  a  force  whose  point 
of  application  and  direction  are  known  beforehand,  and 
might  therefore  be  indicated  graphically  by  the  customary 
arrow  used  to  represent  the  forces  of  mechanics.  On  the 
other  hand  the  affective  tendency  constitutes  a  force  of 
which  neither  the  point  of  application  nor  the  direction 


398  Appendix 

are  predetermined  but  only  the  point  towards  which  it 
tends.  It  is  a  "disposable"  energy  to  be  applied  at  will 
to  this  or  that  act  so  long  as  it  leads  to  the  desired  end. 
Therefore  it  can  be  represented  at  the  same  time  quite 
indefinitely  by  any  of  the  infinite  number  of  arrows 
which  fill  the  entire  volume  of  a  cone  and  converge  at 
its  apex. 

The  reflex  movement  admits  therefore  of  but  a  single 
solution.  On  the  other  hand  the  affective  tendency 
admits  of  an  indefinitely  large  number  of  solutions  so 
long  as  none  of  the  possible  movements  has  been  per- 
formed by  chance  and  given  rise  to  a  choice;  or  when 
there  are  numerous  equivalent  paths  to  the  goal. 

This  possibility  of  many  solutions  constitutes  exactly 
the  "unforeseen/'  the  "antimechanical"  behavior  depend- 
ent on  the  affectivity  or  will,  in  contrast  to  the  predeter- 
mined mechanical  behavior  of  reflex  movements  or  of 
any  such  complex  combinations  of  reflex  movements  as 
certain  instincts  exhibit. 

Finally  it  is  this  fundamental  property  of  the  affective 
tendency  of  constituting  in  some  degree  a  force  grav- 
itating toward  that  environment  or  those  particular  en- 
vironmental relations  which  permit  the  reactivation  of 
certain  mnemonic  accumulations  forming  this  very  ten- 
dency, which  lends  that  environment  or  those  environ- 
mental relations  the  appearance  of  a  vis  a  fronte  or 
"ultimate  cause"  differing  very  essentially  from  the  vis 
a  tergo  or  "actual  cause"  which  alone  is  operative  in 
inorganic  nature.49 

The  organism,  writes  Jennings,  "seems  to  work  to- 
ward a  definite  purpose.  In  other  words,  the  final  result 

49See  W.  James,  Principles  of  Psychology,  I.  pp.  7  f.  London, 
Macmillan,  1901. 


Affective  Tendencies  399 

of  its  action  seems  to  be  present  in  some  way  at  the  be- 
ginning, determining  what  the  action  shall  be.  In  this 
the  action  of  living  things  appears  to  contrast  with  that 
of  inorganic  things."  50 

Now  this  "final  result  of  its  action"  exists  really  from 
the  beginning  in  the  form  of  mnemonic  accumulation. 
For  that  environment  or  those  special  environmental  con- 
ditions to  which  the  animal  is  gravitating  operate  now  as 
vis  a  fronte  in  so  far  as  they  were  formerly  vis  a  tergo  and 
in  so  far  as  the  physiological  activities  then  determined 
by  them  in  the  organism  have  left  behind  a  mnemonic 
accumulation  which  now  itself  constitutes  the  real  and 
true  vis  a  tergo  moving  the  living  being.51 

Thus  it  is  clear  that  one  and  the  same  explanation 
applies  to  all  the  "finalism"  of  life.  For  from  the  onto- 
genetic  development  which  creates  organs  that  cannot  per- 
form their  functions  until  the  adult  state,  to  the  tendency 
of  all  physiological  states  determined  by  certain  environ- 
mental conditions  to  remanifest  themselves  at  the  first  ap- 
pearance of  phenomena  usually  preceding  these  conditions, 
but  in  no  wise  constituting  them;  from  the  perfect  way 
in  which  the  organism  in  its  entirety  is  morphologically 
adapted  to  its  environment  before  the  latter  can  exercise 
its  formative  influence,  to  all  the  wonderful  formations 
and  special  structures  so  exactly  adapted  to  all  the  most 
probable  conditions  to  which  this  organism  might  later  be 
exposed ;  from  the  simplest  reflex  motions  that  are  directed 
so  perfectly  toward  the  preservation  and  welfare  of  the 
individual  to  the  most  complex  instincts  by  means  of 

50Jennings,  Behavior  of  Lower  Organisms,  p.  338. 

51E.  Mach,  Die  Analyse  der  Empfindungen,  5th  ed.,  pp.  79,  78, 
Jena,  Fischer;  English  edition:  Chicago,  Open  Court  Publishing 
Company,  1897. 


400  Appendix 

which  animals  prepare  in  advance  for  future  conditions  of 
which  they  themselves  are  probably  ignorant — all  these 
"finalistic"  phenomena  of  life,  identical  in  their  nature,  can 
be  explained  as  so  many  manifestations  of  a  purely 
mnemonic  nature,  as  we  have  seen  in  our  earlier  writings 
mentioned  above. 

And  now  in  the  present  essay  we  see  that  affective 
tendencies,  which  are  even  more  conspicuously  "finalistic" 
manifestations,  are  likewise  based  upon  the  mnemonic 
property  of  living  substance,  and  hence  in  the  last  analysis 
upon  the  faculty  of  "specific  accumulation,"  a  faculty  be- 
longing exclusively  to  the  nervous  energy  which  underlies 
all  life. 

This  mnemonic  property,  this  faculty  of  "specific  ac- 
cumulation," which  by  its  absence  leaves  inorganic  nature 
exclusively  in  the  power  of  forces  a  tergo  and  deprives 
it  of  every  finalistic  aspect,  is  on  the  other  hand  every- 
where present  in  organic  nature  and  because  of  its  pres- 
ence makes  the  world  of  life  a  world  apart,  of  which  the 
most  characteristc  elements  cannot  be  explained  by  the 
laws  of  physics  and  chemistry  alone  in  the  limited  sense 
assigned  to  them  to-day. 

EUGENIO    RlGNANO. 

MILAN,  ITALY. 


INDEX 


Abridgment  of  memory  and 
ontogeny,  326. 

Accessory  idioplasm,   137. 

Acclimatization,  371. 

Accumulation,  mnemonic,  377, 
399;  specific,  374,  400. 

Accumulators,  electric  or  nerv- 
ous, 290  ff,  296  ff,  309,  319, 
322,  341  ff;  paired,  341,  353. 

Actinia  equina,  372. 

Adaptation  functional,  124,  127, 
174,  180,  203. 

Affective  tendencies,  358 ;  defined, 
361 ;  eliminative,  365 ;  particu- 
lar, 369;  subjectivity  of,  377; 
originated  by  habit,  378;  dis- 
tinguished from  emotions,  390; 
hypertrophied,  393. 

Affinity,  vegetative,  92 ;  of  differ- 
ent tissues,  90. 

Agassiz,  researches  upon  asym- 
metrical flat  fishes,  217. 

Alessandrini,  results  of  the  ab- 
sence of  the  spinal  cord,  305. 

Allonnes,  d',  Les  inclinations,  376 ; 
39i,  392. 

Amblystoma,  307. 

Amphimixis,   194,   195. 

Amphioxus,  80,  133. 

Amputations,  non-inheritance  of 
effects  of,  169,  174. 

Anachronisms  of  development, 
66,  112. 

Anaesthetics,  43. 


Anentoblastia     (absence    of    the 

entoblast),  112. 
Annelids,  heteroplastic  grafts  in, 

90. 

Anthropoid  apes,  12,  13. 
Antibacterion,  272. 
Arbacia,   101. 

Arrests  of  development,  98. 
Ascidians,  80. 
Ass,  pad  of  fat  in  the  colt  of  the, 

165. 

Assimilation,  332,  336. 
Association  of  ideas,  201,  330. 
Asteria,  60,  101. 
Atavism,  144. 
Atavistic  reversion,  98,  100,  191, 

280. 
Axolotl,  regeneration  in,  20,  307. 

Bachmetjeff;  inheritance  of  al- 
terations, 174. 

Bain;  pleasure  in  killing,  386; 
simple  affectivities  into  com- 
plex, 388;  sentiment  of  justice, 
389;  pursuit  of  pleasure,  394. 

Balbiani  (Note)  fission  in  in- 
fusoria, 54. 

Baldwin ;  choice,  397. 

Bard ;  vital  induction,  231 ;  cell 
proliferation,  230 ;  biogenetic 
theory,  230;  vital  phenom- 
enon, 333. 

Bardeen,  Charles  Russell;  note, 
heteromorphosis,  88. 


401 


402 


Index 


Barfurth;  regeneration,  89; 
straightening  of  the  regener- 
ated tail  of  tadpoles,  307. 

Bathmism,  257,  258. 

Beale,  Sir  Lionel;  number  of 
the  brain  cells,  323. 

Begonia  phyllomaniaca,  83. 

Bernard,  Claude ;  anaesthetics,  43  ; 
irritability,  298,  374;  memory 
in  the  germ,  316;  sensibility 
of  the  nervous  substance,  333 ; 
characteristics  of  life,  337. 

Bert ;  transplantation  of  parts 
of  the  body,  90. 

Biogenesis    of    Oscar    Hertwig, 

233. 

Biogenetic  Law  of  Haeckel,  6, 
11,  77,  99,  221,  222,  240,  285, 
316,  356;  significance,  13. 

Biogen  hypothesis,  335. 

Biophores,  145. 

Blastomeres,  shifting  and  isola- 
tion of,  80,  132,  133. 

Blood,  transfusion  of,  281. 

Blumenbach,  137. 

Bombinator  igneus,  91. 

Bonnet;  regeneration  in  the  sal- 
amander, 19. 

Born;  transplanting  parts  of  the 
body,  91,  114,  128;  studies  of 
growth,  116,  118,  119,  128. 

Brain,  development  of,  200. 

Brooding,  379. 

Brown-Sequard;  inheritance  of 
the  effects  of  injury  in  guinea 
pigs,  166. 

Butterflies,  color  of  scales  of, 
174;  Cope's  experiments  upon, 
256. 

Callosities  of  tame  camels,   165. 
Camels,   callosities  of,  165. 


Castle ;  acclimatization,  371  f. 

Cattaneo  G.  note,  165.  Note, 
166.  note,  181. 

Central  Zone  of  Development, 
16,  25,  53,  61,  65,  77;  structure 
of,  73;  location  of,  71,  73,  75; 
in  plants,  71 ;  formation  of  ,  86. 

Centroepigeneses  of  second  or 
higher  degrees,  72. 

Cephalic  monsters,  65,  114. 

Chabry;  researches  upon  ascid- 
ians,  80. 

Chemical  development,  theories 
of,  149,  276. 

Chemotropism,  335. 

Chicken,  instinct  in  the,  227. 

Chiracanthium  carnifex,  379. 

Choice,  397. 

Chromatin,  78,  82. 

Chromosomes,  78,  354,  355. 

Clock,  stopping  of  a,  382. 

Co-adaptation,  178. 

Coleridge ;  latent  memories,  328. 

Colloidal  ferments,  279. 

Compensatory  growths,  47. 

Completion  of  development,  101, 
1 20. 

Composite  flowers,  72. 

Comte,  August;  Positivistic  phi- 
losophy, 5. 

Conditions  of  inheritance,  286, 
300. 

Coordinated  variations,  187,  210, 
214. 

Cope;  likeness  of  certain  struct- 
ures in  different  races,  205; 
useful  variations,  209  ff ;  the- 
ory of  inheritance,  256  ff,  314. 

Copulation,  366,  385. 

Correlation  networks,  46,  47,  62 
ff. 


Index 


403 


Crabs,  regeneration  of  the  feet 
of,  140. 

Crampton,  H.   E.,   109.     Note. 

Crosses,  good  or  defective  de- 
velopment in,  100. 

Cruelty,  386. 

Crystal-formation  as  compared 
with  formation  of  the  organ- 
ism, 228. 

Cunningham;  colors  of  asym- 
metrical flat  fishes,  217,  308. 

Cuscuta,  247. 

Cyclas  cornea,  60. 

Dallinger;  experiments  in  ac- 
climatization, 371. 

Dareste;  headless  monsters,  113; 
spina  bifida,  127. 

Darwin,  Charles;  20.  Note, 
Xenia,  74;  mixed  races,  100; 
gemmules,  145 ;  pangenesis, 
150,  281 ;  inheritance  in  do- 
mestic animals,  160,  224;  gas- 
tric juice,  206;  theory  of  he- 
redity, 280;  hen  with  plumage 
of  a  cock,  311. 

Darwin,  Francis;  setaria  grass, 
44;  mnemonic  property  of  liv- 
ing substance,  375. 

Dastre;  vital  phenomenon,  338; 
functional  activity  and  rest, 
340. 

Datura  ferox  and  Isevis,  100. 

Davenport ;  acclimatization,  371  f. 

Decisive  experiment  on  inherit- 
ance, 171. 

De  Gros,  see  Durand. 

Delage ;  indirect  ways  of  de- 
velopment, 12;  parallelism  be- 
tween ontogeny  and  phylog- 
eny,  14;  generation,  38;  sec- 
ondary protoplasmic  connec- 


tions, 47;  localization  of 
growth,  48;  unicellular  and 
pluricellular  organisms  alike, 
59;  regeneration,  140,  91 
Note,  125  Note ;  species  forma- 
tion, 216;  indirect  ways  of 
ontogeny,  12,  242;  biogenetic 
theory,  263;  sexual  characters, 
310;  indirect  division  of  the 
nucleus,  354. 

De  Meyer,  see  Meyer. 

Determinants,  (Weismann's), 
122,  125,  127,  131,  136,  139,  142, 

151,      213,      220,      221,      284;     Of 

smaller  growing  power,  212. 

De  Vries;  causes  of  the  spe- 
cificity of  development,  106; 
pangens,  145,  206,  283;  Weis- 
mann's criticism  of,  152; 
chemical  compounds  in  plants, 
206;  preformistic  germs,  133; 
qualitatively  equal  cell  divi- 
sion, 283. 

Differentiation,  histologic,  117, 
124,  273;  correlative,  47,  61, 
104. 

Dimorphism,  310  ff,  366. 

Diplogenesis,  257,  284. 

Disassimilation,  338,  348. 

Dogs  (hunting),  instinct  of,  166. 

Double  formations,  68,  87,  114, 
129,  132,  133. 

Driesch;  Echinus  microtubercu- 
latus,  80;  half  embryos,  no; 
theory  of  organic  develop- 
ment, 243. 

Ducks,  mixed  races  of,  TOO. 

Durand  de  Gros ;  human  poly- 
zoism,  73. 

Dynamic  equilibrium,  120,  293. 


404 


Index 


Echinus  microtuberculatus,  80. 

Economy  of  the  organism,  191. 

Ehrlich ;  immunised  mice,  234. 

Elasticity  of  the  organism,  93- 
96,  98,  218. 

Electric  current,  180;  compared 
with  nervous,  291 ;  oscillating, 
341  ff,  346,  372. 

Electro-chemical   generator,  291. 

Element ;  generic  potential,  291 ; 
mnemonic,  319,  326,  353;  spe- 
cific potential,  77,  79,  89,  92,  98, 
101,  102,  290,  296,  299,  300, 
343,  349,  deposition  of  so- 
matic, 84;  of  germinal,  103; 
vital,  343,  349. 

Eliminative  affective  tendencies, 
365. 

Eliminative  hypothesis,  367. 

Emery,  origin  of  instincts,  200. 

Emotions,  defined,  389. 

Encasement  of  germs,  121. 

Environmental  invariability,  364. 

Epigenesis,  6,  18,  104,  107. 

Errera ;  inheritance  of  alter- 
ations, 172. 

Euglena  reacting  to  light,  364. 

Evolution  (as  opposed  to  pre- 
formation),  104,  105,  119. 

Exner,  instinct  of  hunting  dogs, 
166. 

Fasting;  influence  on  metamor- 
phosis, 50. 

Fear,  origin  of,  388. 

Ferments,  279. 

Finalism,  399,  400. 

Fischer ;  transplantations,  123 ; 
butterflies'  wings,  174. 

Flat  fishes,  asymmetrical,  217, 
308. 

Flechsig,  Kdrperfilhlsphare,  376. 


Flowers,  centroepigeneses  of  two 
grades,  in,  72. 

Fogliata ;  fat  pads  in  asses'  colts, 
165. 

Formative  stimulus,  29,  59. 

Friendship  caused  by  habit,  383. 

Functional  adaptation,  124,  127, 
160,  169,  174,  180,  181,  182,  184, 
194,  196,  202,  203,  207,  208,  21  if 
247,  268,  276,  296,  304,  309-311. 

Functional  stimulus,  15,  94,  102, 
184,  207,  236,  266-268,  289,  290, 
302;  cooperating  with  onto- 
genetic,  305  ff ;  identical  with 
mnemonic,  325. 

Fundulus,  125. 

Galls,  124. 

Gall  flies,  247. 

Galton,  Francis ;  particulate  in- 
heritance, 145;  inheritance,  175, 
224;  investigations  of  the  in- 
heritance of  instincts,  175; 
preformistic  germs  and  trans- 
fusion of  blood,  281 ;  stirp,  282 ; 
influence  of  habit,  384. 

Garten,  Siegfried ;  intercellular 
bridges  in  epithelia,  33  ff. 

Gemmaria  (Haackes),  229. 

Gemmes  (Haackes),  229. 

Gemmules  (Darwin),  145,  281. 

Generator  (see  electrochemical 
generator). 

Generic  element   (see  Element). 

Germinal  elements,  86,  92,  99, 
100,  101,  311. 

Germinal  energies, 

Germinal  substance,  14,  17,  18, 
76,  78,  93,  103,  106,  107,  108, 
121,  144,  148,  154,  157,  201,  217, 
229,  281,  287,  288,  290,  294,  296, 
300,  301,  324,  328. 


Index 


405 


Germinal  tracks,  "Keimbahnen," 
283. 

Germinal  zone,  74. 

Germs,  Gallon's,  145. 

Germs,  preformistic  (see  prefor- 
mistic  germs.) 

Germ  cells,  83,  84,  189,  228-231, 
252,  254,  257,  258. 

Giard;  parasitic  relation  of  off- 
spring to  parent,  378;  brood- 
ing, 379;  lactation,  380;  ma- 
ternal affection,  381. 

Giraffe,  198. 

Goethe,  nature  of  flowers,  72. 

Goldstein,  Kurt ;  influence  of  the 
central  nervous  system  on  de- 
velopment, 76. 

Gorilla,  13. 

Graf,  leech,   125. 

Grafts,  89,  90,  117. 

Gregariousness  caused  by  habit, 
383- 

Gromia  oviformis,  42. 

Gros  (see  Durand  de  Gros). 

Gruber ;  division  of  infusoria, 
54,  58;  stentor  coeruleus,  54, 
55;  unicellular  and  pluricel- 
lular  organisms,  60. 

Guinea  pig,  inheritance  of  the 
effects  of  injuries  in,  166. 

Haacke;  theory  of  inheritance, 
228. 

Haase,  H. ;  regeneration  in  Tubi- 
fex  rivulorum,  140. 

Habit,  origin  of  affective  tenden- 
cies, 378;  influence  of,  384. 

Haeckel;  perigenesis,  259;  his 
theory,  259,  314;  mnemonic 
character  of  plastidules,  316. 

Haeckel's  biogenetic  law  (see 
biogenetic  law). 


Hammar ;  communications  be- 
tween the  cleavage  cells  of  the 
sea  urchin  egg,  39. 

Hansemann ;  nuclear  division, 
355- 

"Harmonicity"   of  Vochting,  89. 

Hartmann,  Eduard  von ;  doctrine 
of  descent,  196. 

Hartog,  Marcus,  353. 

Heidenhain ;  intercellular  bridges 
between  cells  of  different  tis- 
sues, 40. 

Helleborus  niger,  247. 

Hemitherium  anterius,  63. 

Hensen;  memory,  324. 

Herbst ;  sea  urchin,  80 ;  epigen- 
etic  theory,  246. 

Hering;  the  phenomenon  of 
memory,  3i6ff;  the  nervous 
substance  as  the  preserver  of 
memories,  321,  375. 

Heritage  (all  that  is  inherited), 
77,  85,  237,  246,  274,  275. 

Hermaphroditism,  366. 

Hermit  crabs,  181. 

Hertwig,  Oscar;  embryonal 
organs  without  function,  12; 
transmission  of  the  stimulus 
for  membrane  formation,  32 ; 
transmission  of  nuclear  stim- 
uli, 42;  gastrular  invagin- 
ation,  75,  87;  frogs'  eggs,  80; 
shifting  the  blastomeres,  81 ; 
hereditarily  equal  division,  81, 
82;  double  gastrular  imagina- 
tion, 87;  organization  of  the 
egg,  97;  causes  of  the  specifi- 
city of  development,  106 ;  galls, 
124;  new  formations,  136;  bi- 
ogenetic theory,  233  ff;  rejec- 
tion of  biogenetic  law  of 
Haeckel,  242 ;  specific  action  of 


406 


Index 


stimuli,  298;  the  mnemonic 
phenomenon,  316;  the  vital 
process,  337. 

Hertz;  researches,  344,  345,  348. 

Heschenhagen ;  capacity  of 
adaptation  in  the  lower  fungi, 
173- 

Heteromorphosis,  87. 

Heteroplastic  grafts,  90. 

His ;  conception  of  development, 
248. 

Hoffman;  inheritance  of  alter- 
ations, 172-3. 

Hofmeister;  chemical  develop- 
ment, 278. 

Horns,  development  of,  163. 

Hunger;  inheritance  of  alter- 
ations, 172,  361 ;  leads  to  sense 
of  ownership,  387. 

Huxley;  definition  of  plants,  43. 

Hyatt;  shells  of  cephalopods, 
162. 

Hybrids,  99,  144. 

Hydra,  83,  86,  143,  362. 

Hypophysis,  n. 

Hyrtle;  defective  growth,  305. 

Idioblasts,  145. 

Idioplasm,  18,  83,  89,  132,  145. 
236,  239,  255,  316. 

Ids,    (Weismann's),   122. 

Ilyanassa  obsoleta,  109. 

Immunisation,  234,  272. 

Independence  of  parts  with  ref- 
erence to  whole,  376. 

Infusoria,  regeneration   in,  53. 

Inheritance  of  acquired  char- 
acters, mechanism,  289. 

Instincts,  151,  161,  175,  177,  200, 
227,  313,  320- 


Intellect,  an  aid  in  transference 
and  source  of  new  affectivities, 
386  f. 

Intercellular  bridges,  30  ff,  39, 
40. 

Interpolation  of  ontogenetic 
stages,  96. 

Invagination,  48,  49,  258;  Gas- 
trular  double,  87. 

Invariability,  environmental,  364; 
individual,  370;  physiological, 
361,  363,  368;  physiological,  a 
factor  in  social  evolution,  370  f ; 
tendency  to  physiological,  mne- 
monic, 373. 

Involution,  49,  191,  212,  221. 

Irritability,  298,  333. 

Irrito-contractility,   43. 

James ;  emotions,  391 ;  choice, 
397;  actual  and  ultimate  cause, 
398. 

Jastrow;  instinct  in  chickens, 
227. 

Jennings ;  reactions  to  food,  362  ; 
reactions  to  light  and  tempera- 
ture, 364 ;  ameba,  369 ;  organism 
works  for  an  end,  398  f. 

Johnson,  H.  P.,  284,  285. 

Jost;  heteroplastic  grafts,  90. 

Justice,  origin  of,  388. 

Kallima,   185. 

Karyokinesis,  354. 

Kastor ;   structure  of  bone,   126. 

King,  Helen  Dean,  60. 

Kohlwey,  171. 

Lactation,  379. 

Lamarckian    principle,    159,    I75> 

196,  202,  203,  207,  223,  224,  314, 

367. 


Index 


407 


Lange;  emotions,  391. 

Law,       fundamental      biogenetic 

(see  biogenetic  law). 
Lecaillon;  mother-love  of  spider, 

379- 

Le  Dantec;  gastrula,  73;  par- 
ticulate  inheritance,  151 ;  re- 
production, 151 ;  shells  of  ce- 
phalopods,  162;  colors  of  the 
skin,  183;  biogenetic  theory, 
268  ff ;  amblystoma,  307. 

Leech,  125. 

Lehmann's  law,  382. 

Lens   of  the  eye   of  tritons,   28, 

89. 

Lewes ;  nervous  system,  45 ; 
physiological  effects  of  mem- 
ories, 325;  vital  phenomena, 

337- 

Lionel  Beale;   (see  Beale.) 
Lipomata,   from  burden  bearing, 

165. 

Lizard,   regeneration  with   alter- 
ations, 141. 
Localisation   of  growth,   48,   49, 

258. 

Loeb;  fundulus,  125. 
Lombroso,      Cesare ;      lipomata 

from  burden  bearing,   165. 
Love,    conjugal,    389;    maternal, 

378,  389;  sexual,  365,  381,  389; 

parental,  381. 

Macfarlane,  43. 
Mach;  vis  a  tergo,  399. 
Magosphaera  planula,  30. 
Martiny;  structure  of  bone,  126. 
Maudsley ;    impression    upon    a 

mnemonic     centre,     320,    328; 

driving  force  of  the  will,  393. 
Maupas ;  term  "senescence,"  365. 
Maxwell,  348. 


Medusa,  80,  83, 

Membranelles  in  Infusoria,  60, 
284. 

Memory,  251,  261,  262,  316  ff; 
physiological  effects,  324,  375; 
latent,  328. 

Metabolism,  362. 

Metamorphoses,  98. 

Metschnikoff;  phagocytes,  49. 

Meumann ;  impulse  and  restraint, 
392. 

Meyer,  J.  de;  inheritance  of 
alterations,  172,  173. 

Meynert;  brain  cells,  323. 

Mimicry,  184,  185. 

Mimosa,  44. 

Mivart;  evolution,  105. 

Mixed  races,  100. 

Mnemonic  elements  (see  ele- 
ments). 

Mnemonic  laws.  See  "Substitu- 
tion of  part  for  whole," 
"Transference"  and  "Independ- 
ence of  part  with  reference  to 
whole." 

Mnemonic  phenomena,  253,  256, 
262,  299,  316-8,  322,  330,  331, 
356,  363- 

Mobius;  pike  and  gudgeons,  175. 

Molar  movements,  270-272. 

Molecular  movements,  271. 

Monsters,  65,  113,  130,  132,  305. 

Moral  ends,  transference  to,  386. 

Morgan;  regeneration  in  Plana- 
ria  maculata,  87,  135 ;  hybrids, 
101 ;  one  embryo  from  two 
blastulas,  134;  experiments 
with  dogs,  376;  origin  of  ma- 
ternal love,  380  f. 

Mosaic  theory,  119. 

Mosaic  work,  109,    28. 


Index 


Motion,  difference  between  plants 

and  animals,  370. 
Mule,   transverse  stripes   in  the, 

100. 

Miiller,    Erik;    eye    lens    in    the 

tritons,  28. 
Miiller,    G.    E. ;    stopping    of    a 

clock,  382. 
Mus  decumanus,  Mus  rattus,  Mus 

sylvaticus,  90. 
Myxomycetes,  29,  372. 

Nageli ;  idioplasmic  network, 
230;  unfolding  of  the  anlagen 
of  the  idioplasm,  239 ;  Weis- 
mann's  objection,  242,  243; 
general  and  mnemonic  idio- 
plasm, 255;  the  mnemonic 
•phenomenon,  316. 

Nature,  former  habit,  384. 

Navicula  brevis,  reaction  to  light, 
372. 

Neal ;  acclimatization,  372. 

Nerve  cells,  262. 

Nervous  energy,  29,  33,  41,  43, 
45,  46,  48,  49,  50,  70,  77,  79,  86, 
98,  256,  289,  299,  319,  330-332, 
336,  340,  344,  357-  Specific,  62- 
63- 

Nervous  coordinations,  45,  251, 
252,  253. 

Nervous  current,  nervous  flux, 
32,  35,  36,  37,  39,  41-43,  102, 
295-  297,  299,  300,  319,  322,  325, 
346,  347,  348,  356;  compared 
with  electric,  289-292;  specific, 
16,  102,  290,  374;  oscillating, 
341  ff. 

Nervous  discharge,  41,  292  ff, 
322,  342,  343,  346,  348»  352,  357- 

Neuters  among  the  insects,  178, 
187,  312. 


Newts,  arrests  of  development 
of,  99 ;  regeneration  in,  19,  140. 

Nisus  formativus,  137. 

Nostalgia,  383. 

Nuclear  division,  79,  83,  92,  132, 
246,  283,  350,  354. 

Nuclear  somatisation,  18,  24-26, 
27,  79,  83,  84,  89,  92,  119,  262, 
297,  299. 

Nuclei,  somatic  and  germinal,  84, 
85- 

Nussbaum;  division  of  Infuso- 
ria, 54;  form-determining  en- 
erg}-,  59;  continuity  of  the 
germ  cells,  189;  inheritance  of 
acquired  characters,  190. 

Oilier;  transplantation  of  bony 
tissues,  90. 

Omphalosite  monsters,  113,  114. 

Ontogenetic  stimulus,  51,  59,  94, 
101,  306,  309. 

Optimum  conditions,  tendency 
towards,  372. 

Orr;  alteration  of  the  nature  of 
growth,  96;  crosses,  100;  bio- 
genetic  theory,  251-256;  com- 
parison with  the  mnemonic 
phenomenon,  316;  vital  phe- 
nomenon, 332. 

Osborn ;  phagocytes,  49;  influ- 
ence of  fasting  on  transforma- 
tions, 50;  adaptive  reactions, 
209;  latency,  217;  colors  in 
pleuronectids,  217. 

Osmotic  currents,  270. 

Ostwald ;  term  "stationary,"  361 ; 
pleasure,  395. 

Overcrowding,  effects  of,  197. 

Ownership,  sense  of,  387. 

Pangenetic  theory,  206. 


Index 


409 


Pangens,  144,  145,  151,  153,  206, 
283. 

Panmixia,  184,  190-192. 

Paramoecium  caudatum,  59;  re- 
acting to  temperature,  363. 

Parasites,  191,  378. 

Paniculate  inheritance,  144,  150, 
151,  153,  154,  156,  302. 

Passion,  defined,  393. 

Perigenesis,  259. 

Periodicity  of  biologic  functions, 
350,  351- 

Peripatus,  39. 

Perrier,  Edmond ;  polyzoism,  73- 

Persistence,  effect  of,  383. 

Pfeffer ;  formation  of  cell  mem- 
branes, 31. 

Phagocytes,  49. 

Phonograph,  300. 

Physiologic  unit;  Spencer,  225, 
227,  228;  the  organism  a,  236, 
252. 

Physiological  invariability,  361, 
363,  368 ;  a  factor  in  social  evo- 
lution, 370  f ;  tendency  to,  mne- 
monic, 373. 

Pieron;  oysters  close  when  ex- 
posed to  air,  364. 

Pigeons,  crosses  in,  100. 

Pillon ;  parental  love,  382. 

Pineal  gland,  n. 

Placenta,    96. 

Planaria  maculata,  87,  88,   135. 

Plasticity  of  the  organism,  91, 
94-96,  218. 

Plastids,  Ledantec's,  268  ff. 

Plastidules,   Haeckel's,  259,   316. 

Pleasure  and  pain,  394. 
Pleuronectids,  217. 
Pluteus,  101. 
Polymorphism,  311  ff. 
Polyommatus  phlaeas,  182,  284. 


Polyzoism,  human,  73. 

Post-generation,  21-27,  29,  63, 
81,  96,  134. 

Posthumous  action  of  the  nu- 
cleus, 56,  290. 

Potential  elements  (see  ele- 
ments). 

Preformation,    6,    106,    119,    120, 

153- 
Preformistic  germs,  106-108,  126, 

133,  144,  147-152,  206,  224,  237, 

280,  284,  300. 
Primula   acaulis,   152. 
Propitiatory  affectivities,  388. 
Protective   colors,    182  ff. 
Protective  polychromatism,  182. 
Pulst;  inheritance  of  alterations, 

172. 

Quinton;  tendency  to  chemical 
invariability,  369. 

Rabe,  J. ;  structure  of  bone,  126. 
Rana    arvalis,    Rana    esculenta, 

Rana  fusca,  91,  118. 
Rapidity  of  division,  75. 
Ray;   inheritance  of  alterations, 

172. 
Recapitulation    of    phylogeny    in 

ontogeny,  IJ,  12,  216,  218,  220, 

228,  243,  250,  260,  263,  268,  273, 

280,  285,  316,  327,  331,  356. 
Reciprocal  action  of  parts  of  the 

organism,  106. 
Regeneration,  19,  20,  28,  29,  54, 

88,  112,  132,  135,  136,  280,  307; 

cenogenetic,  I39-H3- 
Rejuvenescence  of  Infusoria,  353 ; 

of  vital  elements,  343. 
Religious    sentiment,    origin    of, 

388. 
Remodeling  of  tissues,  135. 


4io 


Index 


Renda;  passions,  393. 

Reserve  idioplasm,  85,  117,  132. 

Resonator,  321,  344-346,  353- 

Reversion,  atavistic  (see  atavis- 
tic reversion). 

Rhomboidal    gemmes,   229. 

Rhythmicity  of  biological  func- 
tions, 350,  351. 

Ribbert ;  compensatory  growth, 47. 

Ribot ;  the  mnemonic  phenom- 
enon, 318;  elements  of  mem- 
ory, 320;  memories,  322;  de- 
pendence of  memory  on  nu- 
trition, 324;  Wundt's  experi- 
ment, 325;  abridgment  of 
memories,  326;  latent  mem- 
ories, 328,  329;  rigorously 
serial  order  in  development, 
331 ;  selfishness  of  sexual  love, 
366;  reproductive  instinct  sub- 
ject to  perversions,  376;  af- 
fective life  dependent  on  brain, 
376;  paternal  love  in  animals, 
381 ;  nostalgia,  383 ;  law  of 
transference,  385;  material  and 
ethical  analogies,  387;  religious 
sentiment,  388;  motion  in  nas- 
cent state,  391 ;  passions,  393 ; 
pleasure  and  pain,  394,  395. 

Rignano,  Eugenio ;  influence  of 
the  central  nervous  system  on 
development,  76;  new  mne- 
monic theory,  note,  317. 

Ripening  of  sex  cells,   102. 

Romanes ;  minus-variations  and 
plus  variations,  101. 

Roux;  indirectness  of  develop- 
ment, 1 1 ;  trophic  action,  37 ; 
correlative  differentiation,  47; 
ontogenesis,  48 ;  ontogenetic 
stimulus,  51;  half  embryos, 
61  ff,  134;  mosaic  theory,  68, 


109,  119;  regeneration  of  bi- 
sected frog  embryos,  89; 
elasticity  of  development,  66, 
95 ;  anchronisms  of  devel^ 
opment,  66;  half  embryos, 
96,  97;  self  differentiation 
and  corelative  differentiation, 
104,  124;  half  embryos,  108, 
119;  regeneration  in  tritons, 
112;  opposing  O.  Hertwig, 
112;  double  formations,  68, 
114,  134;  symmetrical  planes, 
115;  on  the  researches  of  Zahn 
and  Fischer,  123;  structure  of 
bone,  126;  size  of  cells,  131; 
self  regulating  mechanism,  95, 
132;  post  generation,  21  ff,  96; 
differentiation,  139 ;  speech 
muscles,  161 ;  structural  rela- 
tions of  the  tissues,  203 ;  tran- 
sition from  aquatic  to  terres- 
trial life,  21 1 ;  distorted  frog 
embryos,  66,  95,  219;  correlated 
development,  210;  theory  of  in- 
heritance, 224 ;  functional  stim- 
ulus, 266-267;  chemical  devel- 
opment, 276;  embryonal  and 
adult  life,  303;  absence  of  the 
spinal  corn,  305  note ;  accel- 
erated development,  306;  the 
vital  phenomenon,  332 ;  attrac- 
tion of  the  chromosomes  by 
the  centrosomes,  355;  on  sex- 
ual hunger,  365. 

Rubin,  Richard;  relation  of  the 
nervous  system  to  regenera- 
tion, 76  note. 

Rush;  latent  memories,  329. 

Sachs;  synergids,  41. 
Saint-Hilaire,   Isidore   Geoffroy; 
headless  monsters,   113. 


Index 


411 


Salamander,  arrest  of  develop- 
ment of,  99;  regeneration  in, 
19,  140. 

Schmitt;  transplantation  of  bony 
tissues,  90. 

Schneider;  starfish,  364. 

Schopenhauer;  will  of  the  spe- 
cies, 367. 

Schubeler;  inheritance  of  more 
rapid  development  of  barley 
seeds,  172. 

Shuberg;  connection  of  cells  of 
different  tissues,  40  note. 

Schultze,  Oskar;  double  forma- 
tions produced  from  frogs' 
eggs,  133. 

Sea  urchin,  80;  protoplasmic 
connection  of  the  cleavage 
cells,  39- 

Sedgwick;  eggs  of  Peripatus, 
39;  the  body  as  a  syncytium, 
39,  230. 

Self  differentiation,  104,  115,  119, 
124,  139. 

Self-preservation,  369,  388. 

Self  regulating  mechanism,  95, 
98,  132,  135,  307. 

Semon,  Richard;  memory  as  un- 
derlying principle,  317  n,  375. 

Sequard;    (see  Brown-Sequard). 

Sergi;  emotions,  391. 

Setaria  grass,  44. 

Sexual,  instinct,  365  ff,  381,  389 ; 
vanity,  385. 

Sherrington;  spinal  dog,  376; 
muscular  accompaniment  of 
emotions,  391 ;  reflex  move- 
ments, 397. 

Shifting  of  blastomeres,  80;  of 
parts  of  embryos,  65. 

Social  evolution,  370. 

Somatic  theory,  375. 


Spallanzani;  regeneration  in  the 
salamanders,  19. 

Species,  morphologic  indications 
of,  146. 

Specific  accumulation,  374,  400. 

Specific  potential  elements  (see 
elements). 

Spencer,  Herbert;  germ  plasm, 
148;  Punjabi,  164;  polemic 
with  Weissman,  187,  211;  plus 
and  minus  variations,  190; 
taste  sense  in  the  tongue  papil- 
lae, 194;  physiological  units, 
225 ;  Hertwig  agrees  with  him, 
241 ;  fertilization,  352 ;  effect  of 
persistence,  383  f ;  anticipation 
cause  of  covetousness,  387 ;  de- 
velopment from  brute  instincts, 
389. 

Sphaerechnius,  Morgan's  investi- 
gation of,  134. 

Spider,  mother-love  of,  379. 

Spina  bifida,  126. 

Stahl ;  Myxomycetes,  372. 

Standfuss;  inheritance  of  altera- 
tions, 174. 

Stationary  physiological  condi- 
tion, 361,  364,  368,  377- 

Stentor,  54  ff,  284. 

Stimuli,  action  of,  298;  func- 
tional— see  Functional  stimu- 
lus, ontogenetic  (see  Ontoge- 
netic,  stimulus). 

Stirp,  Galton's,  282. 

Stoichactis  helianthus,  362. 

Stout ;  emotions,  390. 

Strasburger ;  chromosomes  divi- 
sion of,  79;  combination  of 
paternal  and  maternal  charac- 
ters, 156. 

Subjective  illusion  of  free  will, 
394- 


THE  UNIVERSITY  LIBRARY 

UNIVERSITY  OF  CALIFORNIA,  SANTA  CRUZ 

SCIENCE  LIBRARY 

This  book  is  due  on  the  last  DATE  stamped  below, 


NOV  1 7  1971 

REC'D  NOV  1 6 
NOV  2s  1973 


REC'D  6 1979 

REC'D  MAR  2  0  1979 


50m-4,'69  ( J79  48sS  )  2477 


QH431.R6Sci 


3  2106  00252  2503 


